In March 1935, only two years after he came to power in Germany, Adolf Hitler openly defied the Treaty of Versailles imposed on his country at the end of World War I and announced a massive program of rearmament. The plan called for a Reichsluftwaffe, a national air force whose squadrons, as Nazi propagandists said, would put a `steel roof over Germany' and `darken out the sun'. The output of Germany's aircraft industry shot upward from a few hundred planes a year to thousands. By 1939, when Hitler set into motion his schemes for European conquest, the Luftwaffe boasted more than 4,000 frontline combat aircraft, making it the most formidable air force in the world.