Originally scheduled for gunnery school in Boulder, Colorado, plans changed with the war's sudden end. "I was going to be an aerial gunner. A bomber. But it never materialized", he recalled in 2001. After training at an Army camp near Biloxi, Mississippi, he joined the U.S. forces in the Philippines. There Colan rose to the rank of corporal, drew for the Manila Times, and won an art contest. Upon his return to civilian life in 1946, Colan went to work for Marvel Comics' 1940s precursor, Timely Comics. He recalled in 2000, Comics historian Michael J. Vassallo identifies that first story as "Adam and Eve — Crime Incorporated" in Lawbreakers Always Lose #1 (cover date Spring 1948), on which is written the internal job number 2401. He notes another story, "The Cop They Couldn't Stop" in All-True Crime #27 (April 1948), job number 2505, may have been published first, citing the differing cover-date nomenclature ("Spring" v. "April") for the uncertainty. Hired as "a staff penciler", Colan "started out at about $60 a week. ... Syd Shores was the art director". Due to Colan's work going uncredited, in the manner of the times, comprehensive credits for this era are difficult if not impossible to ascertain. In 2010, he recalled his first cover art being for an issue of Captain America Comics; Colan drew the 12-page lead story in issue #72, the cover-artist of which is undetermined. He definitively drew the cover of the final issue, the horror comic Captain America's Weird Tales #75 (Feb. 1950), which did not include the titular superhero on either the cover or inside. After virtually all the Timely staff was let go in 1948 during an industry downturn, Colan began freelancing for National Comics, the future DC Comics. A stickler for accuracy, he meticulously researched his countless war stories for DC's All-American Men at War, Captain Storm, and Our Army at War, as well as for Marvel's 1950s forerunner Atlas Comics, on the series Battle, Battle Action, Battle Ground, Battlefront, G.I. Tales, Marines in Battle, Navy Combat and Navy Tales. Colan's earliest confirmed credit during this time is penciling and inking the six-page crime fiction story "Dream Of Doom", by an uncredited writer, in Atlas' Lawbreakers Always Lose #6 (Feb. 1949). By the early 1950s, he was living in New Rochelle, New York. Around this time he did his first work for DC Comics, then the industry