Promoted to lieutenant colonel he became a senior press aide to General Eisenhower, taking part in the North African, Sicilian, Italian and Normandy landings.
In 1961, he was the executive producer of The Valiant Years a documentary made by ABC television with the cooperation of the BBC.
Subsequently, Le Vien turned the documentary into a book, Winston Churchill: The Valiant Years, published in 1962.
The following year, he was the executive producer of the Black Fox: The Rise and Fall of Adolf Hitler, which won the 1963 Academy Award for Best Documentary Feature.
After his identity was revealed, host Bud Collyer mentioned that Le Vien was working on a documentary of the Windsors.