Following the Battle of Sokovia, which caused the deaths of 177 civilians and $474 billion in property damage, public negativity towards the Avengers and enhanced individuals increased as people around the world demanded for accountability.
After a terrorist attack in Lagos claimed the lives of twenty-six people, eleven of the victims being relief aid workers from the nation of Wakanda, the international community called for the United Nations to create a system of accountability.
Secretary of State Thaddeus Ross approached the Avengers and informed them that the United Nations was currently in the process of passing the Sokovia Accords, which would serve to monitor and police the increasing number of enhanced individuals.
Eventually, Iron Man, Black Widow, Vision and War Machine signed the accords while Captain America, Falcon and the rest of the Avengers refused to do so. The United Nations passed the accords and arranged a formal ceremony at the Vienna International Centre in Austria.
Among those in attendance at the ceremony were Black Widow, King T'Chaka of Wakanda and his son, Crown Prince T'Challa. T'Chaka accepted Black Widow's apology regarding the events in Lagos, but was saddened to hear that Captain America wasn't attending.
T'Chaka opened the proceedings with the keynote address, citing Wakanda's involvement in Ultron's plan for global genocide and the recent destruction in Lagos as his reasons for supporting the accords.
T'Challa, who had been observing the speech, suddenly noticed a commotion outside the building and learned that a bomb had been planted in a news van. Despite his attempts to evacuate the room, the bomb decimated the building. As chaos ensued, a wounded T'Challa found his father's corpse and cradled it in his arms.
Following the bombing, T'Challa was crowned King of Wakanda. When security footage "revealed" that Bucky Barnes was responsible for the attack, he set out to avenge his father's death.
Captain America, who was attending the funeral of Peggy Carter in London, learned about the bombing and headed with Falcon to Bucharest, where Barnes had been hiding since the Battle at the Triskelion.
They managed to track Barnes down to a safe house only to learn that T'Challa was also in pursuit. This resulted in a high-speed chase that ended with everyone being arrested by the Joint Counter Terrorist Centre.
Unbeknownst to all, intelligence officer Helmut Zemo had orchestrated the bombing and framed Barnes in his quest to exact vengeance against the Avengers for the death of his family during the Battle of Sokovia.
In chronological order:
- Captain America: Civil War
- Spider-Man: Homecoming Prelude (concurrent events)
- Black Panther (mentioned, flashback)
- Agents of S.H.I.E.L.D.