No one can say exactly how or when the name "Jeep" first came to mean the all-wheel-drive truck the U.S. Army needed urgently for World War II. Theories include Oklahoma oilman slang, a dimension-jumping character from a "Popeye" cartoon and the shortening of the letters G and P from the "general purpose" vehicle requested by the Army. There's even one photo from testing in 1941 that calls it a "peep," which would have been mighty confusing around Easter. Wherever it came from, the Jeep knew where it was headed by Aug. 1, 1941: off to war.

The Jeep was born from a bid by the U.S. Army for a small, all-terrain vehicle with four-wheel-drive. Developed in just seven weeks, with bits of design from three different automakers — Bantam, Willys and Ford — Detroit eventually built more than 1 million for victory in World War II. Ernie Pyle called the Jeep "as faithful as a dog, as strong as a mule and agile as a goat." After the war, Willys-Overland sold them as glorified farm implements, complete with a power-takeoff hitch. Here's an example of the excitement from the Jeep's birth, as it goes through testing around Ford in the winter of 1941.