Close air support (CAS) is the use of military aircraft in a ground-attack role against targets in close proximity to friendly forces. With aircraft serving as "airborne artillery" in direct support of troops, CAS requires detailed integration with the fire and movement of ground forces. Learn how the CAS mission has developed, from World War II to the wars in the Gulf. Discover how aircraft such as the Junkers Ju 87 Stuka and the modern A-10 Thunderbolt II have forged their reputations in the demanding CAS role, and follow the development of their related weaponry.—IMP