During World War II, the United States of America 's Office of Scientific Research and Development (OSRD) commissioned the design and building of a single prototype amphibious vehicle based on the General Motors Corporation (GMC) army truck, simply by enclosing the chassis in a watertight shell and adding a propeller to drive the machine in the water.

The first prototype was started on 24 April 1942 and finished 38 days later. The top brass in the military did not like the result and the project was on the point of cancellation when an order for 2,000 machines was received from the US forces in Europe, planning the D-day landings. Again another set of generals decided that they did not like the result and the 2,000 DUKWs were about to be mothballed

At the final trial organised by OSRD a Coast Guard boat ran aground 1/4 mile offshore in a 60-knot wind. No rescue could be mounted through the heavy surf. In desperation a DUKW headed for the stranded vehicle and in six minutes effected the rescue of the Coast Guard crew, and returned them to the beach.

Two days later the USA Secretary of State for War recommended to the War Cabinet that DUKWs should be built for the D-day landings - "Two days ago on Cape Cod an army truck went to sea and rescued the men from a stranded naval vessel", was the lucky outcome, and set the DUKW on the road (and sea) to fame

Why are they called DUKWs? Just by chance GMC's coding system for military equipment worked out as follows

D -  1942 year code
U -  Amphibious utility vehicle
K -  Front wheel drive; and
W -  Two rear-driving axles

It was only after this classification did the authorities realise that, phonetically, this sounded like 'Ducks', and the appropriate and affectionate nickname for the machine was inevitably born

First used for the Sicily landings in 1943, their most famous exploit was in landing about a third of all men and materials on the D-day beaches

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