Fateful Encounter
A battle with ZAFT submarine forces led by Commander Marco Morassim prevents Kira from fighting alongside Mu and Cagalli in their FX-550 Skygraspers. Cagalli's Skygrasper sustains damage and is forced to turn back, but she encounters Athrun's transport plane; her Skygrasper is shot down, but not before shooting down his transport plane, forcing Athrun in his Aegis to eject from the transport plane. By chance, they are both stranded on the same deserted island.
Aired 08/03/2003EP 23 - Fateful Encounter

Mobile Suit Gundam Seed
C.E. 71: In the midst of war between the Naturals (OMNI) and Coordinators (ZAFT), a unit from ZAFT is dispatched to hijack the Earth Alliance's newly developed mobile suits on the neutral colony of Heliopolis. Orb Civilian Coordinator Kira Yamato attends the technical college on Heliopolis. After ZAFT hijacks 4 of the 5 mobile suits, Kira stumbles upon the last one, Strike, forced to pilot it to save his and his friend's lives. During this confusion, Kira also reunites with his childhood Coordinator friend, Athrun Zala, who ironically turns out to be a ZAFT soldier and one of the hijackers at Heliopolis. Having control of Strike, Kira joins the Earth Alliance boarding the ship known as Archangel, to protect his friends while despairing over becoming the enemy of his childhood friend and people.
Note: An HD remaster was broadcasting starting on December 23, 2011 with two recap episodes cut, including new and updated animation, conversion to 16:9, and updated music.