On February 21st, C.E. 70, Yzak joined ZAFT. He graduated seven months later on September 20th, C.E. 70 and was assigned to the Klueze Team along with Athrun Zala, Dearka Elthman, Nicol Amarfi and Rusty MacKenzie. The light-hearted, comedic Gundam SEED Suit CD 5: Athrun x Yzak x Dearka drama (also turned into a manga, see the media section) takes place some time between their graduation and the start of the series (a four-month span). Yzak is angered to the point of throwing tantrums (as well as objects) after losing to Athrun in chess. His room-mate, Dearka doesn't seem very surprised by either the fact Yzak lost to Athrun, or that Yzak is having this type of reaction to it. Him bringing up a challenge of horseback riding between the two, as well as their results in marksmanship during their time in the academy reveals that Yzak and Athrun have a rivalry going (though this was also mentioned in the Gundam SEED Suit CD 4: Miguel x Nicol drama, where upon meeting Miguel and being welcomed into the Klueze Team, Athrun's and Nicol's mentioning their placements in the academy causes Miguel to wonder if Athrun and Yzak "had a good relationship." Nicol's reply is an exasperated "not good at all.") Chess and horseback riding are things Yzak has a talent in, so he gets even more angry when Dearka suggests he tries to beat Athrun at something he's "good at." This gets Yzak to starts rambling more about his disdain toward Athrun being better at so much when he's younger than him, as well as the fact that his father is the Chairman of Defense, he came in first at the academy, and his fiancee is Lacus Clyne. As opposed to Yzak's mother bring just a representative, Yzak himself coming in second at the academy, and Yzak not having a fiancee. He gets determined, saying that next time he'll crush Athrun for sure.

He doesn't crush Athrun for sure the next time they play chess (in front of a bunch of spectators in the form of their friends and comrades). Cursing and slamming his hands on the table hard enough to knock the pieces over when Athrun declares a checkmate, Yzak stomps away. Athrun and Dearka talk about him, and Athrun has taken note of things like how Yzak taps his fingers and fidgets when he's impatient during a game. Dearka just shrugs it off, explaining to Athrun that that's just who Yzak is, and mentions that maybe Athrun should lose to Yzak on purpose once in a while. But Athrun is opposed to this, since he knows that if he were in Yzak's position, he wouldn't be happy with that and there would be no real meaning or point in playing in the first place. Athrun also thinks Yzak is a very good opponent, and one can never tell how a chess match will turn out each time, but he's a little annoyed that he has to be the one to pick up the fallen pieces after the game. Dearka says not to make him do something like that, since it'd just make him feel worse after losing ... but then, he thinks of something, and asks Athrun if there was anything he wasn't very good at. But sadly, singing and painting aren't things Yzak are particularly good at himself, and he catches on to Dearka's meddling. They're interrupted by Athrun coming into their room and reminding them they're due for a battle simulation. Through constant bickering during the battle you see that they all actually work very well as a team. Later, Yzak enters the room in the same, angry was he had when he lost, and Dearka is prepared for the same song. But it seems, this time, Yzak actually won. Why he's so angry is because before the checkmate, Athrun realized he was beaten and forfeited graciously, taking away Yzak's chance to feel the thrill of a complete victory.

On January 24th, C.E. 71, the Klueze team investigates reports about a new Earth Alliance military satellite being constructed at Lagrange Point 3. But due to bad information, nothing comes of it. They turn back, and on the way obtain intelligence about the Alliance's new mobile suits being developed on Heliopolis. This is where Gundam SEED begins, as ZAFT and the Klueze Team sneak into Heliopolis to confirm the existence of and capture these new mobile suits. It seems that Yzak is doing a lot of the talk and giving out a lot of the orders during this mission, which is something worth noting because of both Athrun's being put in charge later on in the series, and more down the line in Gundam SEED Destiny, Yzak's own ability and maturing to become a competent commander. They capture four of the five mobile suits, and Yzak becomes the pilot of the Duel Gundam. Despite Yzak's reassurance that Athrun and Rusty would be fine, having lagged behind him, Dearka and Nicol, Rusty is killed in battle. And while Yzak has no on-screen reaction, he was affected by his death as Rusty's name comes up later in the series, as well as Yzak's dutifully visiting his grave over two years later. When the raid on Heliopolis advances, Yzak says that he doesn't care about what might happen to the colony as a result of the fighting, because despite them claiming to be a neutral colony, they allowed the Earth Alliance to hold a developmental project of that scale there. After Heliopolis is destroyed, the Klueze Team chases the battleship Archangel and the Strike Gundam - the final mobile suit that they were unable to capture.

Little does Yzak know that the pilot of the Strike is not only a Coordinator, but Athrun's long-time friend, so when Athrun hesitates in battle, he gets angry at him. Yzak is stubborn, and hates the idea of them having to retreat when the Strike is outnumbered four to one, so he ignores the order in an attempt to bring it down, as its power is slowly dwindling. When Athrun's Aegis Gundam temporarilly captures the Strike rather than destroying it, Yzak screams and curses at him (especially because the Strike actually ran out of power, and Yzak was about to give it a finishing blow), and then his mobile suit loses a part of its arm when the Strike is rescued and repowered. When they return to the their battleship, the Vesalius, Yzak pushes Athrun against the wall, and he and Dearka berate him for ignoring orders and causing them to fail. Nicol breaks up the fight, and Yzak storms out of the room. They chase the Archangel to Artemis, an Earth Alliance satellite with a heavy-duty defensive barrier. Yzak is still sore over having failed to capture the Strike and destroy the Archangel once, so is unamused with Dearka's light-hearted attitude about their situation, saying that it would be a disgrace to have absolutely nothing to report to their commander when he returns. Nicol's Blitz Gundam (with the ability to shroud itself) is sent in to infiltrate, but despite their success in doing so, the Strike and the Archangel still manage to escape.

As the Archangel makes it closer to meeting up with one of the Earth Alliance fleets, the Klueze Team (minus Athrun, who had returned to PLANT) discuss another possibility to attack them before they get there. There's only a ten-minute window of opportunity, but Yzak is determined to take it - he calls Nicol a coward who needs to be quiet, and says it's better to look at it as "having a full ten minutes" rather than "having only ten minutes" to attack. The Gundam SEED Novels note how passionate Yzak is about the idea, and how he was aiming for glory at giving their commander the news that they've gone ahead and destroyed the Archangel, and since he and Athrun were gone he could finally get out of his shadow. They go ahead with the plan and launch. This time, they get close to destroying the Archangel as Yzak doesn't let up on attacking the Strike, keeping it too busy to protect it. But then Kira goes into SEED Mode, a "berserker" like state of mind where his focus on battle deep, and his piloting abilities are peaked. He saves the Archangel and disables Yzak's mobile suit by striking it near the cockpit. This results in an explosion inside that cracks Yzak's helmet and injures his face, and they're forced to retreat. Two days later, ZAFT attacks the fleet and Yzak, after fighting with a few people in the medbay, makes his way to the Duel. He's extremely angry and still in pain, but he forces himself on with a newfound oath of vengeance upon the Strike and its pilot.

The Duel is now equipped with its Assault Shroud Armor, giving it better defense and a few more weapons (since Duel was more of a prototype for the others), and Yzak launches to aid in attacking the fleet in order to lure the Strike out. He and Dearka break through the fleet, taking out anything that gets in their way. Due to their attack and the quickly falling defense line of the fleet, the Strike launches again. Yzak instantly goes on the offense, and winds up venturing too close to the Earth, getting caught in the gravity and being unable to return back to space. But even as he re-enters the atmosphere (as mentioned later, a dangerous thing due to the temperature rising in the cockpit - even though Coordinators could survive through it, Kira was bedridden for a short time after as a result), he contiues on with his assault on the Strike. He's thrown back, and aims his beam rifle at it, just as an escape shuttle passes between the two of them - a shuttle full of Heliopolis civilians picked up by the Archangel and evacuated from the Earth Alliance's fleet flagship. Due to the shuttle moving between them, Yzak hesitates and misses his shot. Still filled with angry vengeance from his wound, he turns his rifle on the shuttle under the assumption it was filled with fleeing soldiers and destroys it despite the Strike's effort to protect it. Yzak and Dearka both fall to Earth.

They landed in the Mediterranean, luckily near other ZAFT forces (Gundam SEED Novels), and ended up at the Gibraltar base. Upon contacting Klueze, Yzak mostly stays silent, letting Dearka do the reporting but looking pretty angry. He orders them to stick with the ZAFT forces in the area and aid them in continuing their pursuit of the Archangel. In the Gundam SEED Novels, Klueze is a little more tough on them, blaming their disregard for following orders as part of the reason that the Archangel and the Strike were still in one piece. While Dearka seems for focused on the fact that they're now stuck on Earth, Yzak's mind is still on nothing but revenge. He removes the bandage covering half of his face, revealing the extent of his injury from his battle with the Strike - a large scar running down between his eyes and the right side of his face. Yelling, he declares that they'll find their target, and when they do, he'd be the one to take them down. They stay in Gibraltar for about a week, and are soon sent to Africa to aid Commander Andrew Waldfelt and his forces, who are aiming to take down the Archangel that landed there.

Yzak isn't too used to the Earth - especially the desert sands that Andy is more than used to by now. It's when he meets up with Andy that it's noted that his scar could easily be removed, and that Yzak is clearly keeping it as a reminder and an oath for revenge. Andy's words are to the point and true, which gets to Yzak, and he quickly changes the subject to their pursuit of the Archangel. Yzak seems rather restless, and determined to head out and attack as soon as possible. When they prepare for attack, Yzak approaches Andy, questioning his order to keep him on top of their main battleship, especially when they've had more experience fighting both the Archangel and the Strike. He's quickly shot down by both Andy (asking him if the Klueze Team lets their soldiers object to orders) and his assistant Aisha (who notes that their "more" experience with the Archangel and the Strike is all losing experience). Despite this, Yzak still tries to object, but Dearka stops him and they leave. As they do, Dearka quietly notes that the battle will probably get chaotic, so they'll have plenty of opportunities - Yzak likes the sound of that idea. In the midst of the battle, Yzak leaps from the battleship and into the sand, but due to the Duel's systems not being adjusted for combat on the Earth with its gravity, he doesn't fare very well at all, missing any chance to cross swords with the Strike. Andy is defeated by the Strike, and Yzak stays in Gibraltar for about a week before meeting up with the rest of his team.
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Athrun, Nicol and Klueze all join Yzak and Dearka at Gibraltar. Yzak more or less begs Klueze to let them continue their pursuit of the Archangel as it makes it way to Alaska. Klueze is busy with other operation plans, but relents and allows the four of them to go ahead, placing Athrun in command of their group. Athrun being assigned as their commander absolutely infuriates Yzak, and the moment they're all left alone, he (as well as Dearka) smartly challenge him, openly wondering just how good a job he'll do. There's a small scene in Owaranai Asu E / Neverending Tomorrow for the Playstation 2 that takes place on Gibraltar. Once away from Athrun, Yzak starts complaining about him being put in charge, and Dearka notes that Athrun tends to be careless on the battlefield, so if anything were to happen like him being unable to control his subordinates, it was all his responsibility. Despite Yzak's dislike of the situation, he doesn't seem to take well to the smart remark. Despite Yzak's reaction to something like that, when Athrun goes missing two days later en route to Carpentaria, Yzak's doesn't seem particularly distressed by the news. He smugly, sarcastically relays the message of "our first important mission for our glorious team is to search for our own leader," and shrugs, saying that they'll have to begin their search tomorrow. They find him, and soon after, catch up to the Archangel just outside the territory of the neutral nation of Orb.

Due to the fact that the leader of Orb's daughter is on the Archangel, as well as Orb's own help in creating the battleship, they allow the Archangel into their waters, and thereafter send ZAFT a message that the Archangel had quickly left. Obviously, none of them believe the announcement, and Yzak is particularly angry about the lie, but Athrun explains that their situation is very different from the one in Heliopolis, so there was really nothing they could do about it without concrete proof. Since their situation is complicated, it's decided that they would sneak into Orb to search for evidence of the Archangel's whereabouts. Yzak smirks, and decides to go along with this plan, but notes that he would go about it in a much more forceful manner if he were the one calling the shots. He also makes a remark about the possibility of meeting Strike's pilot face to face, but considering his reaction to learning about who that is later on in the series, it's not a sure thing that Yzak has caught on to something being off about Athrun and his connection to Kira. They sneak into Orb, but find no signs of the ship. And to Yzak, that's pretty much that. In the Gundam SEED; Astray manga, they also run into the protagonists, who simply ask them for directions, though they get a bit nervous when they're approached. Little does Yzak know, however, that Athrun meets Kira, thus giving him the personal confirmation that the Archangel is in Orb. (In the manga, Athrun And Kira's Fierce Fight, they infiltrate Orb as civilians, rather than mechanics) When they return back to their ship, Athrun insists that he is 100% sure it is there, but doesn't elaborate when Yzak demands to know what his proof is. Since it's been two days since then, Yzak is becoming more and more impatient and frustrated about the situation, but as he puts it when Dearka cracks a joke, despite this he's not so simpleminded to attempt any sort of take-over of power. In the Gundam SEED Novels, Yzak additionally thinks about the chances of their ambush failing, Athrun getting demoted and Yzak being given the chance to lead the team to victory.

Yzak is shocked when the Archangel leaves and is identified, and they attack it the moment it leaves Orb's territory. Yzak is the first taken down by the Strike, falling into the nearby waters (the ZAFT Gundams are riding on Guuls, which are atmospheric platforms that help their mechs take to the sky since they're more meant for combat in space). As the battle rages on, the Blitz is destroyed, and Nicol is killed. Yzak makes it onto the nearby landmass just in time to see the aftermath of the battle. Yzak and Dearka assault the Strike in a rage, but it escapes, and they retreat back to their own ship. Yzak is the one who has the most openly emotion-ridden reaction to Nicol's dying - cursing, kicking and punching his locker with the slightest hint of tears in his eyes, screaming at Athrun to the point where Athrun, just as broken up about the event, reacts with physical force. He swears that he'll take down the Strike, after Nicol, Miguel, Rusty and his own injury. In the Gundam SEED Novels, he punches the wall so hard his knuckles start to bleed, and actually cries a lot more than he does in the anime. Yzak, as well as Dearka and Athrun are filled with grief and anger for their fallen comrade, and they launch after the Archangel again, filled with vengeance-bent vigor.

They battle again, and Yzak is knocked off of his Guul as the Duel loses a leg. Even as he falls, Yzak takes shots at the Strike and lands a hit, destroying its beam rifle before the Duel hits the water. Yzak returns to their ship, but is the only one to do so. Athrun's Aegis self-destructed, and Dearka's Buster was defeated and captured. Despite this, Yzak still approaches their captain, asking about them and if they've gotten any word from either one of them yet. He's told they recieved an order from Klueze to return, and that Dearka and Athrun were both missing - from their point of view, they lost communication with the Buster, and after reports of an explosion, lost contact with the Aegis as well. Still, Yzak presses, asking about possible emergency signals and insisting that they both can't be dead, since they weren't wearing ZAFT's elite red uniforms for nothing. But the captain refuses him, explaining that being in red, he should understand their own situation - being ordered to return, as well as Orb moving to that same area. Yzak isn't happy about this, but relents. The next day, Orb, who finds Athrun alive, returns him to their ship. Yzak doesn't openly show any relief, yelling to him that he has some nerve coming back like this. Athrun tells him that he destroyed the Strike, and Yzak looks relieved that the cause of so many of their problems is now gone.

Yzak returns to Carpentaria base with Athrun, and Athrun is promoted and reassigned in that two week span. Before he leaves, Yzak meets up with him, telling him that his turn will come soon enough, and he can't believe that someone like him was promoted to the special forces. Athrun responds my extending a hand, apologizing for how things turned out and thanking Yzak for all of his help. Though the two always had a sort of rivalry going on, they were both still comrades (and their rivalry aside, they could even possibly get along), Yzak responds in kind and takes the offered hand. Still feeling a bit jealous by Athrun's glory, Yzak tells him that the next time they fight together, Athrun would be the one serving under Yzak, and that he better not die before that time comes - Yzak's own way of wishing him well. Two days later, ZAFT initiates Operation Spit-Break in hopes to take out a good chunk of the Earth Alliance. To all of their soldiers, the intended target for this operation was to be Panama, and at the very last stages they change the target to Alaska - which is the Earth Alliance's central headquarters. Yzak remarks on the tactic, calling it very clever. Since the Earth Alliance is expecting an attack on Panama, their forces would all be set up there, leaving their Alaska base vulnerable. "This will finish off those Naturals for sure." Due to the sudden change in plan, the attack starts three days later.

The ZAFT forces descend onto the Alaskan base, Yzak in the fray. The Archangel, having arrived at their intended destination, is sent out to fight as well. While the Duel takes a short break to resupply, Yzak reports his actions to Klueze happily. Klueze mentions that they can't get past the main gate because of the Archangel's actions, and suggests that Yzak move to help out in that area. Yzak thanks him, and excitedly turns to relaunch and change his position. He attacks the Archangel, and though in the main series a GiNN is about to wipe out the bridge, in the Gundam SEED Manga, it's Yzak and Duel in its place. Regardless, the attack is stopped by the Freedom Gundam - Kira Yamato's new unit. Kira calls out to all of the forces, explaining to them that something called the Cyclops System was about to be activated, self-destructing the Alaskan base - and warns all forces to move away from the area immediately. Yzak doesn't listen, attacking the Freedom and yelling that he's not going to fall for something like that. The Duel is overpowered by the Freedom, and Yzak comes dangerously close to dying from a strike to the cockpit, but Kira changes his hit-point, cutting both of the Duel's legs off and kicking it into the water to be retirved by friendly forces. Yzak, who was full aware of Freedom's oncoming, fatal attack, is rescued by fellow ZAFT forces, and he looks back to the mobile suit, wondering why it didn't go for the killing blow. The Earth Alliance seemed to have known of ZAFT's last minute target change, and set up a giant radiation weapon underneath their base. Its activation takes out a huge amount of the already large number of ZAFT forces that were sent in to attack.

After the tragic loss at Alaska, ZAFT desperately attacks the Earth Alliance base in Panama and destroy their mass driver, cutting off that area's ability to launch shuttles into space. Also, due to a new weapon system that renders their mobile suits useless, the Alliance is overwhelmed by their forces. Many of them, realizing defeat, exit their bases and come out of their cockpits, hands raised in surrender. However, after having just lost so many at Alaska, the ZAFT soldiers aren't sympathetic in the least, killing even them. Yzak watches these actions from a distance, not partaking in them himself but rather wondering how they could find any fun in hitting targets that can't move or fight back. During the battle in Alaska, Raww Le Klueze captured Fllay Allster, a Natural that traveled along with the Archangel, whose father was an influential member of the Earth Alliance. Since then, he'd been keeping her with him, dragging her along wherever he went. Eventually, Yzak asks him about her, curious about the way Klueze has been treating her - letting her roam around the ship and follow him around, giving her her own sleeping quarters - he wonders why she isn't being treated as a captive. Klueze simply answers that war is a very complex thing, having more to it than just firing at one another. He says that he'd been searching for a key, and finally found it, which doesn't seem to enlighten Yzak to much of anything.

Lacus Clyne, daughter of PLANT's former chairman and idol pop-star is branded a traitor after letting Kira Yamato take their newly-developed Freedom Gundam. The Clyne family had always been very well-respected by all Coordinators, so despite their exile, Lacus taps into broadcast signals all over PLANT, trying to spread their messages of peace. Especially because with Athrun's father, Patrick Zala as the Chairman of PLANT, his leadership relies more on fighting to win, rather than searching for the most peaceful method to end the war. Yzak remarks that he has a hard time believing somebody like Lacus would ever do something like betray PLANT and the Coordinators. Klueze replies, saying that her influence on people are exactly why her followers and helpers are using her, and that Yzak shouldn't allow himself to be tricked by them as well. He adds that one should never lose sight of what they're fighting against (which is an important sentiment to keep in mind, as many characters in the series, especially Yzak in Gundam SEED Destiny, believe that one should never lose sight of what they're fighting for). Yzak prepares to return to space after that - still unhappy with the situation with Fllay as a captive, but still confused and skeptical about Klueze's special treatment of her. When he returns to space, Yzak casually asks about ZAFT's new GuAIZ mobile suit model. The mechanic he speaks to mentions that if they do well, they'll eliminate the Naturals in no time, and Yzak's reaction to this was to simply turn around before he finishes speaking, looking a bit agitated.

At this time, Lacus Clyne and her followers steal one of ZAFT's new battleship, joining up with the destroyed Orb's last hope, the Kusanagi, as well as the Archangel - that joined up with Orb after being left for dead as decoys in the battle in Alaska. They form a third, neutral faction that wants to end the war, but don't agree with the extreme ways both ZAFT and the Earth Alliance are going about things. In this faction are Kira Yamato, Athrun Zala and Dearka Elthman, as well as Andrew Waldfelt - and they all hide out at an abandoned colony called Mendel. During a briefing on the situation, Klueze tells Yzak that Athrun is now his enemy, and asks if he can shoot him. Yzak is hesitant and looks torn for a moment, but replies that he'll shoot down any traitor. The Earth Alliance launches an attack on the three-ship alliance, and Klueze orders Yzak to launch with him to the Mendel colony to gather information. When they enter the colony, they cross paths with the newly-restored Strike and the Buster. Yzak, under the assumption that Dearka was killed after the battle outside of Orb, attacks the Buster, hating that a Natural was piloting Dearka's unit. With a counter to stop Yzak's attack momentarilly, Dearka calls out to him, and Yzak is shocked upon hearing his voice. He's happy that he's alive, but it dawns on Yzak that it really is Dearka so he lashes out, demanding to know why he's fighting alongside the Archangel and the Strike. The Freedom appears, and Yzak, filled with confusion and anger, tries to attack it. Dearka stops them, telling Kira that he'd handle the situation with Yzak, and Kira says he hopes their situation doesn't turn into what happened between him and Athrun. When the Freedom leaves, the Buster opens its cockpit, and Dearka asks Yzak if the two of them could put their weapons down and talk.

Yzak gets out of the Duel to meet Dearka face to face, but pulls a gun on him, saying that he's not naive enough to believe an enemy so easily. Dearka's question to him is a simple "am I your enemy?" and tries to reason with Yzak, who stubbornly blocks off the attempts, saying that Dearka was the one who went off to fight with them and become his enemy. In the Gundam SEED Novels, Yzak's thought process is a very confused one, wondering how somebody he was friends for so long with could do this to him. Dearka explains that he could no longer just listen to the orders from his superiors and fight in a war where they were expected to kill off all the Naturals. Yzak is shocked when Dearka tells him that the Freedom's pilot is the one who used to pilot the Strike, that he was a Coordinator just like them, and that he had been friends with Athrun since they were younger. They're meeting is cut short by the battle growing closer to the colony, and Yzak receives an order from Klueze to return. He keeps his gun raised, and Dearka turns to leave, telling him that if he thinks anybody not in ZAFT is his enemy, to shoot him. Instead of doing so, being extremely conflicted with the situation, Yzak just tries again to tell Dearka that he's being decieved. Before leaving, Dearka tells him he wonders which of them was really being decieved, and adds that if it was possible, he'd like the two of them not to fight. Yzak is left alone, confused and angry, but goes to help Klueze and his damaged unit back to their ship, the Vesalius.

As the neutral faction and the Earth Alliance continue to fight, ZAFT launches and jumps into the battle, with their given target as the Eternal. Yzak launches, as ordered. But, thinking back his encounter with Dearka, he is distraught about doing so. When he crosses paths with the Buster, Yzak pauses, and the two simply pass each other without fighting. The battle, already stressful on Yzak, only gets worse, when the Eternal and Kusagani break through ZAFT's defenses and destroy the Vesalius - the ship Yzak had been on since the very start of the series. At this point, Yzak, while still following orders, seems overall torn with his situation. Dearka's words, while not impacting Yzak to make any real moves, have at the very least gotten through to him and are making him think. During the battle, the Earth Alliance (mainly, the Blue Cosmos anti-Coordinator extremists) gets ahold of the technology to create Neutron Jammer Cancelers (Neutron Jammers were created by ZAFT and sent to Earth to stop the use of anything nuclear powers - mainly as a counter when the Earth originally destroyed the PLANT, Junius 7 with a nuclear weapon in the Bloody Valentine incident), and ready to launch an offensive. During this time, Yzak is appointed as a commander of his own squadron. The Earth Alliance, with use of nuclear weapons, destroy one of ZAFT's space fortresses.

With the huge, new threat of PLANT being completely destroyed now than nuclear weapons were once again able to be used, ZAFT launches to try and take out the Earth Alliance before they're able to do so. Yzak, leading his team, also launches, and they fight against their fleet, as well the three Extended-piloted Gundams. The Earth Alliance launches their nukes toward PLANT in the midst of the battle, and Yzak rushes toward them, desperate and trying his hardest to get close enough to take as many of them as he can out. He also yells for the others to not let a single one of them hit PLANT. The Earth Alliance Gundams stand in their way, taking out their forces and blocking Yzak and the Duel in every way they can. The Freedom and the Justice enter the battlefield, equipped with the METEOR system and stop the weapons before they hit their intended targets. They're followed by the neutral faction's three-ship alliance, and together with Yzak and the rest of the ZAFT forces, stop all of the Alliance's following attempts to fire upon PLANT. In retaliation, ZAFT reveals the GENESIS - a huge gamma ray laser cannon capable of obliterating all targets in its path. Yzak gets the order to retreat from the area before the weapon of mass destruction fires, and in a suprising action, calls out to the Justice, Freedom and their forces, warning them about the oncoming attack and to get out of the way.

The results of GENESIS's attack shock Yzak, and he along with the other ZAFT forces get some rest, after almost 40% of the Alliance forces are taken out and they're forced to pull back. While the rest of ZAFT rejoices, Yzak runs into his mother, who is one of PLANT's Supreme Council members. She explains to him that after GENESIS fires its second shot, the war should finally come to an end, so Yzak should finally have rest after so much fighting. When she speaks the words "the future is ours," Yzak looks worried, and thinks back to his meeting with Dearka. He begins to ask his mother what the target of GENESIS's second shot is, most likely worried that it could very well be Earth. But before he can finish asking her that, they call the already busy Ezaria away. Before she leaves, she tells Yzak that he should take it easy, and that she'll make sure that his team is sent further away from the front lines, because he'll have a more important job to attend to when the war ends. Yzak seems frustrated, having not been able to really speak to his mother at a length and get the answers to the questions running through his mind. Waiting for their next deployment, Yzak watches the distant explosions from continuous battle from a window. However, when he and his team launch into the battle, they join the mix of ZAFT, Alliance and neutral faction mobile suits and yet another wave of attempted nuclear attacks on PLANT.

Leading his team, Yzak orders not to let a single shot through, and with the Justice and Freedom, he once again fights to destroy the nukes threatening his home. Yzak is confronted by the Earth Alliance's Raider Gundam, and detained from firing at the nukes - he comes close to get overwhelmed by its attacks. A blast knocks the Raider away before it's able to attack again, and Yzak turns to see what rescued him from the pinch; he's surprised to see that it's Dearka and the Buster. The Strike Rogue, piloted by Cagalli Yula Athha and also part of the neutral faction, is attacked by the Alliance's Forbidden Gundam as she works to stop the oncoming nukes. The Forbidden sneaks an attack on her from behind, but before she's hit, the Duel dives in shield-first to deflect the attack, countering an attack on the Forbidden with the help of Dearka. Taking out his beam saber, Yzak goes in for the attack, and the Forbidden gets a close-range shot on the Duel. Dearka and Cagalli are temporarily shocked to see the Duel engulfed in an explosion, but it's not destroyed. With its shield and Assault Shroud armor completely gone now, obliterated from the attack, the Duel emerges from the explosion, piercing the Forbidden through the cockpit and destroying it. The battle exhausts Yzak, but he fights on, despite that on top of the fact that the Duel is now down a shield and its armor. With GENESIS able to fire one more shot, the neutral faction move to destroy it before it destroys the Earth. Being in ZAFT, Yzak moves to protect any offense or break-through of his forces, but is stopped by Dearka who simply stands in his way. The two don't attack each other.

Yzak stays in place, not daring to force his way past Dearka, even though the others have gone ahead to stop ZAFT's GENESIS. The two are near the Archangel, and a mobile suit makes its ways toward them. It's Raww Le Klueze in the Providence Gundam. Klueze, who was one of the people pulling strings and leaking information every which way in the war, is aiming for humanity to destroy itself through war, and is now making his move to ensure that this happens. He aims to stop the Archangel and the neutral faction from meddling in the battle between PLANT and Earth, and when he gets close enough, Yzak sees the unit as one of ZAFT's, but notes that he doesn't know it. Dearka moves to attack Klueze and defend the Archangel, but the Buster gets almost fatally disabled by its attack. When the Providence moves on to battle the Freedom, Yzak makes his way to Dearka's disabled unit to help him. But when he gets to Dearka, they're both attacked by the Raider, whose pilot is going into a withdrawal from the drugs the Extendeds are given to perform. Yzak's only remaining weapon - his beam rifle - is destroyed, leaving the both of them with hardly any defense. Still, Yzak cover's Dearka as best he can, desperately trying to fire the Duel's head-mounted cannons in any attempt to try and deter their attacker.

The Raider keeps firing at them, and thinking fast, Yzak notices that one of Buster's cannons is still mounted to the suit. Grabbing the cannon, Yzak yells that he won't lose to the Raider and the two fire at one another in a final attempt at either killing or being killed. The Duel gets a shoulder hit and is knocked back along with the Buster, but the Raider takes a direct hit and is destroyed. The Duel runs out of the last of its power, its Phase Shift Armor powering down, but Yzak and Dearka are now safe, despite exhausted from their close encounter with death. In the Gundam SEED Novels, Yzak is confused, speaking impulsively to Dearka's thanks and saying that it wasn't as if he was helping him in particular. However, he also thinks that this battle needs to end, and not just for the protection of PLANT anymore, so Yzak has finally opened his eyes to the reality of the situaton that Dearka had been trying to help him see. Yzak brings Dearka back to the Archangel, and is seen toward the end of the battle, having gotten the Duel power-replentished and resupplied there. Ironically, the shield the Duel is seen holding when it relaunches is the Strike Gundam's. There are no more attacks to the Archangel, so nothing is confirmed in that direction, but when the battle is over, the Duel is still within the general vicinity of the ship - possibly even protecting the ship (after all, he had risked himself to save Dearka who is on it, as well).

The GENESIS is destroyed before it can fire on the Earth, and a cease-fire is announced between ZAFT and the Alliance. In the Gundam SEED After Phase, an epilogue released a few months after the end of the series, Yzak is seen back on PLANT in a council uniform, serving his government. Dearka is also back on PLANT and by his side. In Gundam SEED Destiny, Yzak speaks of problems they went through after the end of the first war due to their actions in it (defecting, killing civilians, etc), so it's not known when exactly the epilogue takes place. However, I personally assume before, due to the fact that the council would have needed many people to make up for the spots that were needed after the coup and reorganization of power, as well as Dearka wearing his red ZAFT uniform in the epilogue. Though one would assume that Yzak continued his work as a council member until getting promoted to a commander of his own battleship and squadron and returning to the front lines, there is no canon information about what happens in the two year span between where we end here and where Gundam SEED Destiny begins.