The Battle of Seoul was a battle in the capital city of South Korea, Seoul, in the year 2054. The battle was between the armed forces of North Korea and South Korea, with the latter being supported by troops from the United States Marine Corps.
The battle began when North Korea invaded Seoul in 2054, causing a large amount of devastation to the city. Even as the battle raged, reinforcements from the United States Marine Corps deployed in Drop Pods from airships high above the city, sending thousands of American troops into the battle zone, among them Jack Mitchell and his best friend Will Irons, who had only joined the Marines six months ago. The drop pods almost immediately came under fire from anti-aircraft weaponry, leading to the loss of several pods. When the pod that carried Mitchell and Irons's pod was hit by anti-aircraft fire, they were forced to make their way through a building in order to enter LZ Epsilon, where they were originally supposed to land.
After fighting their way through North Korean forces, along with dealing with a swarm of drones, the squad came across a squad of Atlas Corporation soldiers that were escorting a VIP out of the city. Eventually they arrived at their target, a North Korean Havoc launcher that the North Koreans were using to take out major roads. Though the demolition team that the squad was supposed to link up with had been wiped out, the squad was able to advance and destroy the launcher, at the cost of Irons's life and Mitchell's arm.
Following the destruction of the launcher another division of Marines arrived in the city and began assisting in the offensive to push the North Koreans back into the border.
Though the South Koreans and Americans were victorious, the cost was heavy; 6000 Marines were killed in four hours, along with many South Korean civilians. Will Irons was also killed, and Mitchell lost his arm in the explosion of the Havoc launcher. Afterwards Mitchell left the Marines to work for Atlas, with Will's father Jonathon Irons, the company's CEO, offering to replace his arm.
It is unkown what the aftermath of the war was, whether North Korea was conquered, the war ended back at the 38th Parallel, or a settlement was forced. Though it can be implied that North Korea was conquered because Jonathan Irons labels it as a country that ATLAS built an infrastructure.