Key Point: German confidence was too high in their air force capabilities.
In the mid-1930s, Nazi Germany had a problem. Its twin-engined medium bombers, such as the Heinkel 111, had a range of perhaps 1,500 miles. However, the Luftwaffe's single-engined fighter plane, the Messerschmitt Bf 109, had a range of only 400 miles (it wasn't until mid-World War II that fighters carried drop tanks). Before 1939, airpower enthusiasts believed "the bomber will always get through" enemy air defenses, but the Germans also realized they needed a fighter capable of escorting bombers all the way to the target and back.
Their solution was the Messerschmitt 110, a twin-engined fighter that looked more like a small bomber. With a range of 1,500 miles for the early models such as the Bf 110C, it was far more heavily armed than single-engined fighters, with up to four cannons and four machine guns firing to the front, plus a rear gunner with a machine gun to ward off attacks from behind. Remarkably, with a speed of around 350 miles per hour, the Bf 110 was also as fast or faster than many early World War II fighters.
Yet there is never a free lunch in aircraft design. Carrying all that extra fuel meant a bigger, heavier aircraft. A bigger, heavier aircraft required two engines and two propellers, which added even more weight. The result was that the Bf 110 weighed more than four tons, or twice that of the Bf 109.