In May 1964, U.S. Strike Command launched Joint Exercise Desert Strike, the largest military war game since World War II, a two-week training exercise that simulated a nuclear air and ground battle between the fictional governments of Nezona and Calonia over water rights in the Colorado River watershed south of Las Vegas. Two joint task forces, Mojave and Phoenix, involving 100,00 U.S. Army and Air Force personnel and using more than 900 aircraft and 500 tanks, were mobilized to fight for their respective governments. The exercise introduced official war cabinets for each country to add realism and a political dimension to decisions about when nuclear or chemical weapons should be used. On May 25, 1964, the 1st Battalion "Tomahawks," commanded by Lt. Colonel Robert S. Dickson of the 501st "Geronimo" Parachute Infantry Regiment, 101st Airborne Division "Screaming Eagles," parachuted 30 miles behind enemy lines near this vicinity and seized a critical pass held by enemy armor units before an umpire halted the exercise shortly after contact was made. Desert Strike also produced new tactics for military river crossings on a nuclear battlefield, requiring numerous crossings along a broad front across the Colorado River rather than a single concentrated troop crossing to reduce the effects of a theater-wide nuclear detonation. The maneuver took place across more than 13 million acres of public and private land in the deserts of California, Nevada, and Arizona at a cost of 54 million dollars, or 540 dollars per man, and thirty-two participants lost their lives during the exercise.