But he could not stop the nationalization of his Mexican oil fields in 1938. President of Mexico Lazaro Cardenas was not to be bribed. President Cardenas refused to bow to Monroe's threats; he put the future of his nation above his own survival. Monroe could not get his assassins within range of the president before the brave Mexican completed the nationalization. And then Monroe could not take revenge: even if he could have killed President Cardenas, the assassination would not have regained Monroe's holdings; and further, the assassination would have risked war between Mexico and the United States, when the American government wanted Mexico as an ally against the European fascists. Secret memos revealed that only personal intervention by President Roosevelt and several senators convinced Monroe he would serve the interests of the United States and the Allies by accepting his Mexican losses.

But Monroe's compliance had a price. Unknown to the public and other defense industries, the War Department exempted Monroe's industries from competitive bidding. World War II made Tate Monroe a billionaire.

Newspaper and magazine writers created an American legend of Monroe's life. A poor boy who wrenched wealth from the Texas frontier by his own strength and daring made for sensational reading. As a man, his exploits filled the pages of the financial sections and the Hollywood gossip columns, as one day he led his workers to recapture a remote oilfield from communist revolutionaries, and the next day he took to bed an actress twenty years his junior. Heard in the rumor mills were the sounds of jazz and starlets' laughter in the primitive camps of his isolated enterprises. But there were other stories that would never appear in newspapers or magazines. Filed in locked cabinets of government agencies and the "Capitalist Atrocity" stacks of leftist agitators, these other stories detailed the annihilation of Indian tribes, spoke of "examples" made by chainsaw mutilation, "police actions" fought with Thompson submachine and Browning machine guns against machetes and rocks. The use of a "field-expedient" napalm — crude oil mixed with gasoline and dropped from a thousand feet in 50-gallon drums — became a standard device in Monroe's so-called Indigenous Education Program.