The Eagle Squadrons were three fighter squadrons of the Royal Air Force (RAF) formed with volunteer pilots from the United States during the early days of World War II (circa 1940), prior to America's entry into the war in December 1941. With the United States still neutral, many Americans simply crossed the border and joined the Royal Canadian Air Force (RCAF) to learn to fly and fight. Many early recruits had originally gone to Europe to fight for Finland against the Soviet Union in the Winter War. Charles Sweeny, a wealthy businessman living in London, persuaded the British Government to form an RAF squadron composed of Americans. (His uncle, also named Charles Sweeny, had been working along similar lines, recruiting American pilots to fight in France.) Sweeny's efforts were also coordinated in Canada by the World War I air ace Billy Bishop and the artist Clayton Knight, who formed the Clayton Knight Committee, which by the time the United States entered the war, had processed and approved 6,700 applications from Americans to join the RCAF or RAF. Sweeny and his rich society contacts bore the cost (over $100,000) of processing and sending the men to the United Kingdom for training. Training The basic requirements for those interested in joining the Eagle Squadron were a high school diploma, being between 20 and 31 years of age, eyesight that was 20/40 correctable to 20/20, and 300 hours of certified flying time. These requirements, with the exception of the flight time, were not as strict as those required for service in the United States Army Air Corps, which was a reason for some of the pilots joining the squadron. Most Eagle Squadron pilots did not have a college education or prior military experience. Once in Britain and having passed basic flight training, the new pilots were sent for advanced operational training to an operational training unit (OTU) for two to four weeks to learn to fly Miles Master trainers, Hawker Hurricanes, and Supermarine Spitfires before being ostensibly commissioned as RAF officers and posted to front-line RAF fighter squadrons. The American pilots assigned to the Eagle Squadrons never renounced their US citizenship and although they wore the uniforms and held the rank titles of RAF officers, their dress and duty uniform tunics were modified with the Eagle Squadron patch, a white bald eagle flanked by the letters "ES" for Eagle Squadron. Formation and evolution