This terrific Geoff Isherwood illustration is of the very obscure Marvel super-team, Freedom's Five. They first appeared [in flashback only] in The Invaders #7 (July 1976). Intended solely to help establish some heroic back history for the newly introduced British Invader,Union Jack, the team also incorporated an actual, former one-shot Marvel hero, the Phantom Eagle - here's the skinny:
From 1914 to 1918, a group of five Allied heroes of unknown background fought together as the Freedom's Five. (Left-to Right) The Silver Squire, Sir Steel, the Phantom Eagle, Union Jack and the Crimson Cavalier waged war against the Germans, their allies, and their superpowered agents, such as the vampire Baron Blood.
Unfortunately, nothing more is known about the Freedom's Five; their origin has not yet been revealed, nor have any more of their exploits.