Because future adversaries are likely to look for alternative means to challenging the U.S. Air Force (USAF) in the air to counter U.S. airpower, a recent RAND study for the USAF investigated those means. As part of that study, this historical effort sought to better understand past, present, and future ground threats to air bases. In the course of the research, it became clear that attacks on air bases were much more frequent and successful than is commonly appreciated. For this reason, the history of these attacks is pertinent to future USAF operations. This report presents a comprehensive overview of ground attacks on air bases from the first known attacks in 1940 to the most recent in 1992. The objectives, tactics, and outcomes of those attacks are analyzed to identify lessons learned and their applications to future conflicts. In particular, this report identifies the attack techniques that proved most difficult to counter and offers some suggestions for improving air base defenses against them. The five primary conclusions of this study are as follows: The most common air base attack objective was to destroy aircraft; seventy-five percent of the 645 attacks used standoff weapons; standoff attacks have proved extremely difficult to counter; reliance on non-air force services for air base defense proved problematic for Britain's Royal Air Force (RAF) on Crete, the German Luftwaffe in North Africa, and the USAF in Vietnam; small forces using unsophisticated weapons have successfully destroyed or damaged over 2,000 aircraft.