After the United Kingdom declared war in 1939, Niven returned to Britain and rejoined the Army. He was alone among British stars in Hollywood in doing so; the British Embassy advised most British actors to stay, many were over the age for military service and did not have Niven's military education and experience.[16] Niven was re-commissioned as a lieutenant in the Rifle Brigade on 25 February 1940,[17] and was assigned to a motor training battalion. But he wanted something more exciting, and transferred into the Commandos. He was assigned to a training base at Inverailort House in the Western Highlands. Niven later claimed credit for bringing future Major General Sir Robert Laycock to the Commandos.
David Niven commanded "A" Squadron GHQ Liaison Regiment, better known as Phantom.
Niven also worked with the Army Film Unit. He acted in two films during the war, The First of the Few (1942) and The Way Ahead (1944). Both films were made to win support for the British war effort, especially in the U.S.. His Film Unit work included a small part in the deception operation that used minor actor M. E. Clifton James to impersonate Field Marshal Montgomery.
During his work with the Film Unit, Peter Ustinov, though one of the script-writers, had to pose as Niven's batman. (Ustinov also acted in The Way Ahead.) Niven in his autobiography explained that there was no military way that he, as a lieutenant-colonel, and Ustinov, who was only a private, could associate, save as an officer and his servant, hence their strange "act". Ustinov later appeared with Niven in Death on the Nile (1978).
Niven took part in the Invasion of Normandy, arriving several days after D-Day. He served in the "Phantom Signals Unit", which located and reported enemy positions, and kept rear commanders up to date on changing battle lines. Niven was posted at one time to Chilham in Kent.
Niven remained close-mouthed about the war, despite public interest in celebrities in combat and a reputation for storytelling. He once said: "I will, however, tell you just one thing about the war, my first story and my last. I was asked by some American friends to search out the grave of their son near Bastogne. I found it where they told me I would, but it was among 27,000 others, and I told myself that here, Niven, were 27,000 reasons why you should keep your mouth shut after the war." Niven also had special scorn for the newspaper columnists covering the war who typed out self-glorifying and excessively florid prose about their meagre wartime experiences. Niven stated, "Anyone who says a bullet sings past, hums past, flies, pings, or whines past, has never heard one--they go crack!"[11]
He gave a few details of his war experience in his autobiography, The Moon's a Balloon: his private conversations with Winston Churchill, the bombing of London, and what it was like entering Germany with the occupation forces. Niven first met Churchill at a dinner party in February 1940. Churchill singled him out from the crowd and stated, "Young man, you did a fine thing to give up your film career to fight for your country. Mark you, had you not done so − it would have been despicable."[11]
A few stories have surfaced. About to lead his men into action, Niven eased their nervousness by telling them, "Look, you chaps only have to do this once. But I'll have to do it all over again in Hollywood with Errol Flynn!" Asked by suspicious American sentries during the Battle of the Bulge who had won the World Series in 1943, he answered "Haven't the foggiest idea . . . But I did co-star with Ginger Rogers in Bachelor Mother!"
Niven ended the war as a lieutenant-colonel. On his return to Hollywood after the war, he received the Legion of Merit, an American military decoration. Presented by Eisenhower himself, it honoured Niven's work in setting up the BBC Allied Expeditionary Forces Programme, a radio news and entertainment station for the Allied forces. [18][19]
