From 1910 until his death from typhoid fever in 1912, Wilbur took the leading role in the patent struggle, traveling incessantly to consult with lawyers and testify in what he felt was a moral cause, particularly against Curtiss, who was creating a large company to manufacture aircraft. The Wrights' preoccupation with the legal issue stifled their work on new designs, and by 1911 Wright airplanes were considered inferior to those of European makers. Indeed, aviation development in the U.S. was suppressed to such an extent that when the U.S. entered World War I no acceptable American-designed airplanes were available, and U.S. forces were compelled to use French machines. Orville and Katharine Wright believed Curtiss was partly responsible for Wilbur's premature death, which occurred in the wake of his exhausting travels and the stress of the legal battle.