The legendary Spitfire, developed independently by the Supermarine Company, and only later sold to Britain's Air Ministry, is only one example. With its smooth lines, load-bearing metal skin, and heavy eight machine-gun armament, the Spitfire was revolutionary.
As it became clear that appeasement had failed, Britain, France, and Germany began the race to build modern planes. The Spanish Civil War, in which the modern aircraft of Germany's Condor Legion battled with older, less-sophisticated types, proved the point: the new aircraft destroyed the old in numbers. The bombing of Guernica and the first deployment of Germany's Stuka dive-bombers were omens of the air war to come.