It is truly fascinating to discover how many of the world's really great aircraft sprang not from years and months of painstaking research and development for a planned requirement, but from an unforeseen event needing an immediate response. Necessity does indeed prove to be the mother of invention in these circumstances, and so it was with the Cobra.

Post-Korea, the US Army had worked on the Airmobile' concept and early experience had validated the effectiveness of the sky soldiers' in Vietnam. In many ways this was as expected: it was only the mode of transport that had changed, the Airmobile divisions were essentially mounted infantry, and the Army had plenty of experience in that (001. Vanderpool's first tactics manual drew heavily on the 1898 vintage Horse Soldiers publication). But just as the horse soldier always needed the cavalry to fully exploit their speed and mobility, so their twentieth-century counterparts found a need for armed escort. Theoretically, the Air Force provided the escort. Fast jets were however far from compatible with helicopters, and not able to provide really close-in fire support. Arming some of the helicopters provided a partial answer, but it slowed them down and reduced the number of soldiers that any one lift could insert. A study was therefore initiated with a view to providing an Army solution. Bell, meanwhile, was a few steps ahead.

The advent of the turbine-powered Huey had revolutionized Army Aviation, making Airmobile a practical proposition. Bell was of course heavily involved in the field-introduction of the type, and had formed its own ideas on an armed version, their concept being essentially an armed scout.