Ducks come from DUKW, a military acronym that designated the vehicle as amphibious military personnel carriers. D Stands for the year it was designated, 1942; U for its amphibious nature; K for its all-wheel drive; and W for its dual rear axles.
Land - Military
DUKW's were created following the attack on Pearl Harbor as a means to transport supplies from ships to areas that did not have port facilities. DUKW's were first used operationally during the invasion of Sicily. Nearly 90% of all supplies came in by DUKW on the vital second and third days of the invasion. D-Day brought a force of 2000 DUKW's to the Normandy coasts. The fleet was an essential element in the strategic surprise of the enemy which assumed the Allies needed a port to make an effective landing. DUKW's are standard 2 1/2 ton GM trucks in a water-tight shell with an added propeller.