Christman's career in comics was a brief one as the medium was only in its infancy when he left it. In 1936 he created a feature titled "The Spinner" in which a police detective would relate unusual cases from his career to listeners. The Spinner spun about into various magazines under the Centaur imprint and others.
The big development for Christman's career in 1936 came when the famous photorealist artist Noel Sickles left his newspaper strip Scorchy Smith, an adventure series featuring the titular maverick pilot Scorchy. Christman replaced Sickles.
While still creating Scorchy, in 1938 Christman created an adventure hero of his own for DC Comics: The Sandman, a figure garbed in a gas mask who would put his enemies to sleep by use of a gas gun. It proved to be a popular enough feature during the war and the character would become a permanent part of the developing DC Universe through his membership in the Justice Society of America, but Christman would never know Sandman was his artistic legacy; in 1938 he left Scorchy Smith & Sandman behind and joined the US Navy's American Volunteer Group. Like Scorchy, he became a pilot, serving in the group known as "The Flying Tigers."
On January 23, 1942, Christman's squadron went into battle over Rangoon, Burma against a much-larger attack group of Japanese fighter planes. During the combat, Christman's plane was hit in its engine. It wasn't the first time Christman had lost a plane to combat and been forced to bail out. Once again, Christman bailed out and opened his parachute, but a Japanese pilot strafed him mid-air; one of the bullets went through his neck and killed him before he reached the ground.
Here's to you, Mr. Christman.