Beginning with "Our Army at War" #32 (March 1955), Kubert began to freelance again for DC Comics, in addition to Lev Gleason Publications and Atlas Comics, the 1950s iteration of Marvel Comics. By the end of the year he was drawing for DC exclusively. DC editor Julius Schwartz assigned Kubert, Robert Kanigher, and Carmine Infantino to the company's first attempt at reviving superheroes: an updated version of the Flash that would appear in "Showcase" #4 (Oct. 1956). The eventual success of the new, science-fiction oriented Flash heralded the wholesale return of superheroes, and the beginning of what fans and historians call the Silver Age of Comic Books. In the coming years, Kubert would work on such characters as the medieval adventurer the Viking Prince and features starring Sgt. Rock and The Haunted Tank in the war comic "G.I. Combat". He and writer Gardner Fox created a new version of Hawkman in "The Brave and the Bold" #34 (Feb.–March 1961) with the character receiving his own title three years later. Kubert's work on Hawkman and in "G.I. Combat" would become known as his signature efforts. Kubert's main collaborator on the war comics was writer/editor Kanigher. Their work together on Sgt. Rock is considered a memorable contribution to the comics medium. They introduced Enemy Ace in "Our Army at War" #151 (Feb. 1965).