Attack on the IFID Headquarters

"This is for dropping half a building on my face!"

- Crossbones to Captain America

The Attack on the IFID Headquarters was an open confrontation between the Avengers and Brock Rumlow, a former HYDRA agent who was determined to exact revenge against those involved in his downfall.

Background
"There are no prisoners with HYDRA. Just order. And order only comes through pain. Are you ready for yours?" "Man, shut the hell up!"

- Brock Rumlow and Sam Wilson

During the Battle at the Triskelion, Rumlow was pinned under rubble after a Helicarrier crashed into the side of the building. Rumlow survived but gained severe facial scars and was subsequently hospitalized.

Several months later, after learning about the death of Alexander Pierce, Rumlow escaped from the hospital where he was staying. Recovering items from S.H.I.E.L.D.'s research and development labs, he set up an arms sale in order to draw HYDRA operatives 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 aligned himself with several mercenaries, unaware that Captain America and the Avengers were trying to track him down.

Battle
Seeking to draw out the Avengers, Rumlow traveled to Lagos, Nigeria and planned to steal a biological weapon from the Institute for Infectious Diseases. However, Captain America became aware of the planned attack and informed the other Avengers.

Upon arriving in Lagos, Scarlet Witch and Black Widow went undercover at a local cafe while Falcon positioned himself on a rooftop that overlooked the city. After noticing an incoming garbage truck was quickly approaching the IFID, Falcon deployed the Redwing only to realize the truck was a battering ram.

By then, however, the "truck" had driven through the entrance and Rumlow's mercenaries had opened fire on several security guards. As poisonous gas slowly flooded the building, Rumlow quietly made his way to the third floor and found the bioweapon he was looking for.

The Avengers then converged on the building and proceeded to take out several of the mercenaries. Falcon used the Redwing to find and confirm Rumlow's location before informing Captain America.

Using her powers to lift Captain America onto the third floor, Scarlet Witch then focused on venting the gas out into the open air while the others proceeded to deal with the remaining mercenaries.

Cap battled his way to catch Rumlow, as the team deals with the remaining mercenaries outside. But Steve was too late, as Rumlow made out with the bioweapon. Natasha then intercept and use her Bite on Rumlow, but had no affected on him, claiming that he no longer feels pains. He then tried to kill her by dropping a grenade in the truck, along with his own men, but she fought her way out and use one of there bodies to shielded herself from the blast. As Rumlow escaped, he gave the bioweapon to one of his men and told them to lose the truck, as they were splitting up to lose the Avengers.

While Falcon, Scarlet Witch, and Black Widow set out to find the bioweapon, Captain America confronted Rumlow and learned that the former STRIKE commander blamed him for his injuries.

Meanwhile, Black Widow managed to locate the bioweapon and confronted the mercenaries tasked with maintaining it. When they threatened to kill everyone in the surrounding area unless she surrendered, she reluctantly complied. The Redwing suddenly appeared and subdued them while Black Widow secured the bioweapon.

Cap was overpowered by Rumlow's gauntlets, but managed to destroy them and beat him to submission. Cap took off his mask and see his face is horribly burnt. He asked who was Rumlow's buyer, but then he revealed that Bucky Barnes still remembered him. Rumlow then activated a suicide bomb attached to his vest and detonated it to take Cap and a few civillians along with him.

Wanda used her powers to contain the blast. However, while attempting to displace it, she moved the blast too close to a nearby building, killing several relief aid workers from Wakanda.

Aftermath
With public opinion increasingly divided following the Battle of Sokovia, the destruction in Lagos was deemed a public relations disaster. Several international politicians, among them Wakanda's ruler King T'Chaka, called for the United Nations to create a system of accountability. President Matthew Ellis held a press conference where he pledged his support towards apprehending the people responsible.

Secretary of State Thaddeus Ross brought the Avengers together and informed them that the United Nations was in the process of passing the Sokovia Accords, which would serve to monitor and police the increasing number of enhanced individuals.

The team became divided over the accords, with Captain America vehemently opposing them due to his mistrust of government agencies and Iron Man supporting them due to his guilt over the destruction of Sokovia.

Despite this, the United Nations arranged a formal ceremony at the Vienna International Centre in Austria. Among those in attendance were Black Widow, King T'Chaka and his son Crown Prince T'Challa. As King T'Chaka made the keynote address, a bomb detonated and resulted in the deaths of T'Chaka and several delegates.

Security footage revealed that the Winter Soldier was responsible and Captain America set out to bring him in, only to learn that his former childhood friend was innocent. This resulted in a citywide manhunt that started the Avengers Civil War.