Overstretched from the start of the Second World War in 1939, the Royal Navy acquired First World War surplus destroyers from the United States Navy and embarked on a massive programme of construction, building and buying aircraft carriers, escort carriers and frigates and corvettes, building up a powerful submarine arm and, almost from scratch, re-creating the naval air arm taken from it in 1918. The service had to learn fast. By the war's end the Royal Navy had grown from its pre-war strength of 129,000 to 863,000 men. Its fleet had also grown from 12 to 61 battleships and cruisers, seven to 59 aircraft carriers, and 100 to 846 destroyers, by 1945.
