What Did You Do In the War, Mama? is set in 1917 when the powers of Europe are locked in a lethal war. Casualty numbers are enormous. There seems no way out of the stalemate. One evening, King George V and his advisers, including Prime Minister David Lloyd George, Army Commander of British Douglas Haig, and Munitions Minister, Winston Churchill are poisoned at dinner. Seriously ill, the men can no longer work and it falls to Queen Consort, Mary, to find a solution to this dangerous situation. And the question then becomes - what would happen if women ruled the world?

The incredible true story of how a bunch of writers, artists, set designers, and back room technicians pooled their talents in order to outwit the German High Command and fool Hitler. Espionage, counterespionage, decoy airfields, inflatable tanks, guns, and soldiers are all deployed in the run up to D-Day to create a massive diversion and the strongest possible indication that the landings will be in Calais rather than Normandy. A whole invisible army is conjured up: FUSAG, the First US Army Group. Major General Patton is placed in charge of this army, such is its importance he is detained in Britain for several weeks after the Normandy landings in order to successfully convince Hitler that a second and larger set of landings will be staged in Calais.