By Katie Lange

Army Maj. Theodor Geisel. | Photo credit Army Photo

Dr. Seuss is a story-writing legend in America. It’s hard to find anyone who hasn’t read “How the Grinch Stole Christmas,” “The Cat in the Hat,” “The Lorax” or “Horton Hears A Who!”

But well before those iconic books were written, Dr. Seuss joined the World War II effort on the home front using his real name, Theodor Seuss Geisel.

At first, he drew posters for the Treasury Department and the War Production Board. But by 1943, Geisel wanted to do more, so he joined the U.S. Army. He was put in command of the animation department of the 1st Motion Picture Unit, which was created out of the Army Signal Corps.

There, he wrote pamphlets and films and contributed to the famous “Private Snafu” cartoon series. “Private Snafu” — which stood for situation normal, all fouled up — was a series of adult instructional cartoons meant to relate to the noncareer soldier. They were humorous and sometimes even raunchy.

Photo credit Fran Mitchell/Army Photo

Army Master Sgt. Nekia Haywood reads to children.

According to the National Archives’ Special Media Archives Services Division, Geisel and his team believed that the risque subject matter would help keep soldiers’ attention, and because the Snafu series was for Army personnel only, producers could avoid traditional censorship. Geisel’s cartoons were often featured on Army-Navy Screen Magazine, a biweekly production of several short segments.

One of Geisel’s most significant military works, however, wasn’t animated. It was called “Your Job in Germany” and was an orientation film for soldiers who would occupy Germany after the war was over.

Photo credit Library of Congress

Theodor “Dr. Seuss” Geisel at work on a drawing of the Grinch, the hero of his children’s book, “How the Grinch Stole Christmas.”

Geisel, who was German-American himself, was assigned to write it a year before the Germans surrendered.

According to Geisel’s biography, “Dr. Seuss and Mr. Geisel,” Geisel said he was sent to Europe during the war to screen the film in front of top generals for approval. He happened to be in Belgium in December 1944, when the Battle of the Bulge — Hitler’s last big counteroffensive in Belgium’s Ardennes forest — erupted. Geisel was trapped 10 miles behind enemy lines, and it took three days before he and his military police escort were rescued by British forces.

National Archives staff say it’s possible that the “Private Snafu” cartoons influenced Geisel’s career as Dr. Seuss. In these cartoons, Geisel started using limited vocabulary and rhyme — something noticeable in his later works like “The Cat in the Hat,” which used only 236 words but is one of the best-selling books of all time.

Photo credit Navy Petty Officer 1st Class Julie R. Matyascik/Navy Photo

Air Force Gen. John Hyten shares a “The Cat in the Hat” reading hat before he reads to children.

Geisel left the Army in January 1946, having attained the rank of lieutenant colonel. He stayed in the filmmaking industry for a few years, even working on documentaries and shorts that earned Academy Awards, but he eventually switched to using his pen name, Dr. Seuss, to start writing children’s books.

And the rest, as they say, is history!

- This story originally appeared on defense.gov. It has been edited for style, grammar and brevity.