As was Dan Sickles. His "problematic" relationship with superior officers culminated in his disobeying a direct order at Gettysburg, and imperiling the entire Union position on Cemetery Ridge, as well as getting his command shot to hell. After the battle he insisted that he was solely responsible for the Union victory despite evidence to the contrary.
Sickles killed the younger Key at the edge of Lafayette Park in D.C. After the civil war, Sickles was a leading voice in preserving the key battlefields of the war, particularly Gettysburg. One of the important considerations of shoring up the Gettysburg properties was drawing the boundary between the National Military Cemetery and the local cemetery. Sickles had the fence from Lafayette Park (where he had killed Key) in DC brought to Gettysburg and set between the two.