Nazi crimes against the Jews angered Berman so much that he joined the Canadian Army to go fight them (Pearl Harbor had not yet brought the U.S. into the war). He served in northwest Europe with the 18th Armoured Car Regiment (12th Manitoba Dragoons), a reconnaissance outfit, along with Minnesota friend Nathan Gittlewich. He was well liked. Fellow troopers did not know of his criminal background.
After the war he became a partner with Bugsy Siegel in the Las Vegas syndicate casino The Flamingo.
His daughter Susan Berman wrote a memoir about him, called Easy Street, before her murder in December 2000.