A concept that really came to fruition during the Vietnam War with the advent of the Air Cav (hooyah!) and helicopters such as the Huey and Chinook that meant you could fly in a mix of grunts, light vehicles, artillery and engineer kit, then lift it out again as required.
Yeah, well, you know. As much as I hate to say it... it was the French in Algeria that thought of the methods, tactics and manoeuvres that made airmobile operations viable. People like Bigeard (Of Indochina Dien Bien Phu fame) thought of the tactics and organised their units accordingly. They also fought one of the few (the other one being Malaya) effective counter-insurgency campaigns. It has to be said that in the French case the helicopters were all American. The US 1st Aircavalry division that did so well in the Vietnam war was based on French experience in Algeria. Mel Gibson forgot to mention that in his little film...Typical...
Extremely handy for manoeuvre warfare, although vulnerable if you don't have air supremacy and a healthy SEAD plan.