Hollis was commissioned into the Royal Marine Light Infantry in 1914 and served in the First World War in the Grand Fleet and the Harwich Force . Between the wars he served on the staff of the Commander-in-Chief Africa Station and of the Plans Division at the Admiralty before being appointed Assistant Secretary of the Committee of Imperial Defence in 1936 . He served in the Second World War as Senior Assistant Secretary in the War Cabinet Office . He was present at virtually every major decision during that period , attending all the major conferences — Washington , Cairo , Tehran , Yalta and Potsdam — and was instrumental in establishing what became known as the Cabinet War Rooms ( now known the Churchill War Rooms )
Potsdam
Potsdam Conference
Leslie Hollis