rudder bar. It was an important predecessor of his later Bleriot XI Channel-crossing aircraft of the summer of 1909. World War I World War I served as a testbed for the use of the aircraft as a weapon. Aircraft demonstrated their potential as mobile observation platforms, then proved themselves to be machines of war capable of causing casualties to the enemy. The earliest known aerial victory with a synchronized machine gun-armed fighter aircraft occurred in 1915, by German Luftstreitkräfte Leutnant Kurt Wintgens. Fighter aces appeared; the greatest (by number of air victories) was Manfred von Richthofen. Following World War I, aircraft technology continued to develop. Alcock and Brown crossed the Atlantic non-stop for the first time in 1919. The first commercial flights took place between the United States and Canada in 1919. Interwar aviation in the "Golden Age" The so-called Golden Age of Aviation occurred between the two World Wars, during which both updated interpretations of earlier breakthroughs – as with Hugo Junkers' pioneering of all-metal airframes in 1915 leading to giant multi-engined aircraft of up to 60+ meter wingspan sizes by the early 1930s, adoption of the mostly air-cooled radial engine as a practical aircraft powerplant alongside powerful V-12 liquid-cooled aviation engines, and ever-greater instances of long-distance flight attempts – as with a Vickers Vimy in 1919, followed only months later by the U.S. Navy's NC-4 transatlantic flight; culminating in May 1927 with Charles Lindbergh's solo trans-Atlantic flight in the Spirit of St. Louis spurring ever-longer flight attempts, pioneering the way for long-distance flights of the future to become commonplace. World War II Airplanes had a presence in all the major battles of World War II. They were an essential component of the military strategies of the period, such as the German Blitzkrieg or the American and Japanese aircraft carrier campaigns of the Pacific. Military gliders were developed and used in several campaigns, but they did not become widely used due to the high casualty rate often encountered. The Focke-Achgelis Fa 330 Bachstelze (Wagtail) rotor kite of 1942 was notable for its use by German submarines. Before and during the war, both British and German designers were developing jet engines to power airplanes. The first jet aircraft to fly, in 1939, was the German Heinkel He 178. In 1943, the first operational jet fighter, the Messerschmitt Me 262, went into service with the German Luftwaffe and later in the