The famous subject of World War II graffiti across Europe is one of the most well known images, but also one of the least understood. The phrase “Kilroy Was Here!” and the corresponding drawing became widespread wherever the American military traveled, symbolizing the country’s presence there. However, most-including the American soldiers drawing it-were unsure of its origins.

Because of this mystery, the radio network set up for American Armed Forces decided to cast a wide net, asking its listeners for any information about the cartoon’s creator. The most convincing result is reminiscent of the origins of the phrase “Uncle Sam”, a meat inspector who put his initials US on boxes of meat sent to troops. A ship inspector from Boston, Massachusetts called Kilroy, put his stamp of approval on all ships before sending them off, writing “Kilroy was Here” to assure the crew of their safety. Soldiers ignorant of the phrase’s meaning decided to write it throughout the countries they were fighting in, sparking further Kilroy hysteria. While this is a logical story, its accuracy cannot be fully verified, nor can the cartoon’s country of origin (while it is widely associated with the United States, it also could have originated in Great Britain.)

It appears that American soldiers were not the only ones unsure of its origins. Adolf Hitler, upon seeing the great number of images, ordered a full sweep of Germany to find this character, who he assumed was a quick American spy.