United Nations Vienna office bombing

The United Nations Vienna office bombing was a terrorist van bombing of the United Nations Office at Vienna in 2016, during the ratification of the Sokovia Accords. The bombing killed twelve people, including King of Wakanda T'Chaka, and injured seventy others. Perpetrated by Helmut Zemo, the bombing was intended to divide the Avengers and incite an internal civil war. Zemo framed Bucky Barnes, a former Hydra assassin, for the attack. Zemo was motivated by the loss of his father, son, and wife in the Battle of Sokovia, believing the Avengers to be responsible.

A mass search for Barnes began after the bombing. Barnes was detained in Bucharest and evaluated by Zemo, who impersonated himself as Theo Broussard. Wakanda appointed T'Chaka's son, T'Challa, as king. A photograph of journalist Jeffrey Mace circulated after the bombing, leading to his appointment as the participant of Project Patriot and as the director of S.H.I.E.L.D.