"Rip" Graves was reported dead at Flanders, an exceptionally bloody site in World War I. Graves had actually survived, but when he finally returned to the United States, he found that he'd been honored as the "unknown soldier" at the tomb in Washington, D.C.
Instead of reclaiming his civilian identity, he made the odd decision to take up residence beneath the Unknown Soldier's crypt. In secret, he battled for his country as the Ghost of Flanders.
The Ghost of Flanders wore a Brodie style helmet and patriotic chest plate. His quarters were rather nice for having been somehow secretly installed beneath a national monument. Perhaps this was due to his relationship with contemporary U.S. intelligence. He was last seen in 1942.
The Ghost of Flanders had no super-powers. He was an exceptional hand-to-hand fighter with military training, and handy with throwing knives. He could also pilot planes.