In 1936 his equipment automatically guided an airplane from Paris to Réunion island off the coast of Madagascar, in the first practical demonstration of an aircraft guidance system.

That allows American and European firms to sell mid-range computers, aircraft guidance systems, oscilloscopes and other high-technology goods to former Warsaw Pact nations at will, even though such goods can also be used to design, test and navigate missiles and other weapons.

Ledley started to use SEAC himself for his dental research, but after proving an adept programmer and troubleshooter, he found himself working with SEAC (and later DYSEAC) full-time on a wide variety of projects, including a remote-controlled aircraft guidance system.

Subsequent snooping revealed that between '42 and '45, the assets of the Magna Corporation had quadrupled, due to successful bidding for thousands of government defense contracts: Magna had been the armed forces' prime supplier of bombers, aircraft guidance systems, antiaircraft weapons, tanks and halftracks, even K-ration kits and servicemen's uniforms.