The Battle of Washington, D.C. was a clash between Captain America and the brainwashed Winter Soldier during the HYDRA Uprising. After Arnim Zola revealed that HYDRA was active for the past seven decades, Captain America and Black Widow recruited Sam Wilson to fight alongside them as the Falcon.
- "The 21st century is a digital book. Zola taught HYDRA how to read it. Your bank records, medical histories, voting patterns, e-mails, phone calls, your damn SAT scores. Zola's algorithm evaluates peoples' past to predict their future."
"And what then?"
"Oh, my God. Pierce is gonna kill me."
"Then the Insight Helicarriers scratch people off the list. A few million at a time."
- ―Jasper Sitwell and Steve Rogers
Arnim Zola revealed that HYDRA, despite the defeat of the Red Skull, had been growing inside S.H.I.E.L.D. for the past 70 years to Steve Rogers and Natasha Romanoff, only to result in HYDRA ordering an airstrike on their location, killing Zola.
Rogers and Romanoff laid low in Sam Wilson's apartment, a friend whom Rogers met previously during a morning run. Wilson revealed his past as a parajumper and equipment that he had used during his career in the military. Rogers and Romanoff figured that Jasper Sitwell knew information regarding Zola's algorithm. The trio went to Fort Meade to retrieve the EXO-7 Falcon wings.
On a freeway, the trio took Sitwell to use him to prevent Project Insight and arrest Alexander Pierce, but was disrupted when the Winter Soldier leaped onto their car and attacked them. The masked assassin grabbed Sitwell and threw him into traffic, but Rogers slammed the emergency brake, throwing the Winter Soldier off the car. A jeep with Russian HYDRA mercenaries rammed the car, causing it to struggle across the pavement and tumble. Despite this, Rogers, Romanoff and Wilson survived the crash.
A shootout occurred on the freeway and the trio separated. Rogers defended himself against a rocket launcher using his vibranium shield, but the blast caused Rogers to fly off the bridge into a transit bus, which later crashed on the street below. Romanoff fought the Winter Soldier and the HYDRA mercenaries, but was forced to swing off and underneath the bridge when she was nearly caught in the explosion of a nearby car. Wilson held his ground on the bridge and fought the remaining HYDRA mercenaries with a knife and a stolen rifle. While the Winter Soldier was searching for Romanoff, she revealed herself and shot his eye glasses.
Four mercenaries rappelled down to kill Rogers, but he managed to avoid being hit and grab hold of his shield. Wilson began to aid Rogers in killing the mercenaries. While searching for Romanoff, the Winter Soldier was tricked when hearing her voice behind a nearby car, only for Romanoff to tackle him from behind. After a short fight, the Winter Soldier wounded her in the shoulder when she attempted to evacuate civilians and herself; Rogers attacked him, saving Romanoff from the throes of death.
The Winter Soldier and Rogers fought on the streets until Rogers forced the Winter Soldier's mask to come off. It was then revealed to him that the Winter Soldier was Bucky Barnes, Rogers' long-lost friend during World War II - however, Barnes was clueless as to who he was, as well as his past friendship with Rogers in the 1940s. Now distracted and confused, Wilson and Romanoff attacked Barnes. However, when Romanoff chucked a grenade at the assassin, Barnes mysteriously vanished.
Moments later, the STRIKE team led by Brock Rumlow arrived and were about to execute the three, but Rumlow ordered his men to stand down and merely arrest Rogers, Romanoff, and Wilson, as there were news helicopters filming them. They were then driven away by armored vehicles in heavy restraints to be executed away from public view.
- "It was him. He looked right at me and he didn't even know me."
"How's that even possible? It was like seventy years ago."
"Zola. Bucky's whole unit was captured in '43. Zola experimented on him. Whatever he did, it helped Bucky survive the fall. They must have found him."
- ―Steve Rogers and Sam Wilson
Rogers, Romanoff and Wilson, with the help of Maria Hill, escaped from STRIKE and Hill took them to a hidden facility. While the doctors inside began to treat Romanoff for her gunshot wounds, the three of them were taken to Nick Fury's presence, who was still alive. Fury revealed that he took Tetrodotoxin B, a drug developed as a heart-rate suppressant by Bruce Banner, and they began their plan to take down Project Insight.
As they were preparing, Rogers spoke to Wilson about how Barnes had not recognized him. When Wilson inquired as to how it could have Barnes when he supposedly died around seventy years ago, Rogers theorized that Zola's experiments on him caused him to survive and that HYDRA must have found him after.