Well I don't know about HUGE but they did help build them when production demands for the war effort became too much for Willys-Overland.
When it looked like the US would be joining the European war effort the US Army put out a tender for a small 4WD vehicle, the only company to submit a prototype(and the blue prints) for testing was the American Bantam Car Company.
The design was done by Karl Probst, an American freelance engineer under contract with American Bantam.
American Bantam did get a small contract and made about 2,500 of the Bantam "jeep"(Bantam BRC-40) which mostly went to England and some to Russia.
The US Army liked it but didn't think American Bantam could meet production demands(read kickbacks

).
So they scheduled a test of the Bantam vehicle and invited Willys-Overland and Ford, they also gave both the American Bantam blue prints for the vehicle, "claiming the government owned the design", because of the contact to produce them

Willys-Overland took the hint and submitted their prototype, pretty much an exact copy but with a stronger engine that the Army had requested after testing the first prototype(but didn't tell American Bantam about, best MPG was a spec on the first tender).
So in testing both prototypes side by side the Willy-Overlander won out because of the bigger engine.
Willys-Overland got the contract, and Ford got the overflow "because of elements favorable to Ford within the Quartermaster Corps"(i.e. read kickbacks)
Willys and Ford fought over who's design it was(American Bantam and Karl Probst, Duh), and after the war they fought over the "jeep" name, Willys won that one.
From 1942 to 1945 Willys-Overland had built 361,339 "jeeps"
Ford had built 277,896 "jeeps"
Willys was taken over by Kaiser and then Kaiser was taken over by American Motors then Chrysler took over American Motors.