That(and also the Captain America & U.S.Agent)is the Super-Patriot a.ka. John Walker.Back in the late 80's,Gruenwald introduced this guy as a more gung-ho patriot.He'd been augmented by Professor Power & along with three other augmented guys he came up with Super-Patriot & the Buckies(Bold Urban Commandos).He fought Captain America in a parking lot,claiming that Cap no longer was fit to represent the U.S..Cap barely held his own & there was no clear winner of the fight(Cap #327).
Later,when Cap was asked by the Comission of Super Hero Activities(Cap #332)to once again work for the govt.,John Walker fought a terrorist at the Washington Monument & aced the guy.Cap refused to work for the Comission & was stripped of his Cap identity.John Walker was then asked to be the replacement for Captain America & along with one of his Buckies(Lemar)they underwent training as the new Captain America & Bucky.While Walkers heart was in the right place he was shown to have been a lot more violent & quick tempered than Steve Rogers.Eventually,he ended up being stripped of the Cap identity which was given back to Steve Rogers(Cap #350).
The comission then faked Walkers' assasination at a press conference(Cap #351)so they could then come up with a new identityfor him.Using Steve Rogers black uniform that he wore during the time he wasn't Cap,they retrained Walker as the U.S. Agent.Giving him a new identity(Jack Daniels)& speech therapy so he wouldn't be recognized as Walker,hey placed him in Avengers West Coast as team leader replacing Hawkeye.Later he joined Tony Starks' Force Works team until it was disbanded.He showed up again during the "Maximun Security" storyline a couple years ago & had a mini-series after that done by Jerry Ordway.
