On April 1, 1918, amid the grinding stalemate of the First World War, Britain formally created the Royal Air Force by merging the army's Royal Flying Corps with the navy's Royal Naval Air Service. It was the first air arm in the world to exist as an independent military service, equal in status to the army and navy, reflecting a hard-won belief that air power would decide future wars.
The merger was driven by frustration. British commanders had watched German bombers strike London with near impunity, and the rivalry between the two existing air services wasted resources and coordination at a moment when the war demanded neither. A government inquiry led by South African statesman Jan Smuts concluded that air power was becoming so important it deserved its own ministry and its own service, not a subordinate branch of the older forces.
On the appointed day, roughly 20,000 aircraft and 300,000 personnel were folded into the new force, commanded by the Royal Air Force's first chief, Hugh Trenchard, who would spend the rest of his career defending the idea that airpower belonged to no one but itself. The RAF's pale blue uniform, still worn today, was reportedly chosen partly because vast stocks of blue-grey cloth originally ordered for Russian Tsarist airmen had never been delivered after the Russian Revolution.
The gamble paid off spectacularly two decades later. It was this same institutional independence, and the doctrine it fostered, that allowed the RAF's Fighter Command to organize the integrated radar-and-fighter defense that won the Battle of Britain in 1940.