The Attack on the IFID Headquarters, also known as the Lagos Catastrophe, was an open confrontation between the Avengers and former HYDRA agent Brock Rumlow in Lagos, Nigeria.
During the Battle at the Triskelion in 2014, HYDRA operative Brock Rumlow was pinned under rubble when a Helicarrier crashed into the building. He survived but gained severe facial scars and was subsequently hospitalised.
Several months later, after watching a news report about the death of Alexander Pierce, he assaulted his nurse and successfully escaped from the hospital where he was staying.
Recovering items from S.H.I.E.L.D.'s research and development labs, Rumlow set up an arms sale in an attempt to draw HYDRA out of hiding. Upon learning of their arrival, Rumlow opened fire on them as a way of telling their superiors he was no longer a member of HYDRA.
Taking up the alias "Crossbones", Rumlow went on the run and subsequently aligned himself with a faction of foreign mercenaries, unaware that Captain America and the Avengers were trying to track him down.