flying hours (six months) as FACs in South Vietnam and who would serve six-month tours in Laos. There were always going to be shortages of both personnel and aircraft in the new program. Only six Ravens were assigned between 1966 and 1968 to control the ever-expanding amounts of U.S. airpower being utilized in Laos. Even at the height of the program, when they would control one-third to two-thirds of the tactical air strikes in the Barrel Roll area, there were never more than 22 Ravens. The Ravens flew the entire gamut of U.S. observation aircraft, from O-1 Bird Dogs, and U-17s, to T-28s and, eventually more modern O-2 Skymasters and OV-10 Broncos. Each Raven carried aloft a Laotian observer, who could provide almost immediate clearance for air strikes. On the ground, Laotian Forward Air Guides (FAGs) also called in for air support missions. See-saw war From 1965 through 1968, the war in the northeast followed the monsoon cycle, with dry season communist offensives followed by wet season Hmong (and later Thai) counteroffensives. Each year the conflict slowly escalated. PAVN would introduce more (and better equipped) units and the U.S. would counter by the application of more airpower, producing a strategic stalemate. In July 1966, PAVN and Pathet Lao forces consisting of three infantry regiments, one independent infantry battalion, and an artillery battalion, seized the town of Nam Bac and then established a defensive line north of Luang Prabang. The communist advance, however, was gradually eroded due to the destruction of its supplies by air power. Vang Pao's forces counterattacked in August, driving the enemy back to within of the North Vietnamese border. More communist forces then entered the battle, forcing the Hmong back. The communists moved out to take the Plain of Jars again in 1967. Laotian victories were few and far between and by the end of the year the situation had become critical, even with the support provided by the American and Laotian Air Forces. PAVN, having a complete understanding of the American military system, began to attack TACAN facilities. U.S. intelligence indicated that between December 1967 and August 1968, the combined strength of PAVN and Pathet Lao forces increased from about 51,000 to over 110,000. The PAVN contingent comprised an estimated 34,000 combat troops, 6,000 advisors, and 18,000 support troops. On 6 December Lima Site 44 was overrun and on the 25th PAVN forces captured Lima Site