ジャール平原
As the Laotian Civil War flared, the Central Intelligence Agency established a secret guerrilla army in the Plain of Jars. Interposed between the communist settlement around Xam Neua and the Royal Lao Government in Vientiane, the Hmong military irregulars fought to hold on to their traditional territory, and to preserve Laos. After the failure and defeat of Operation Pigfat and Operation Raindance in early 1969, the communists had overrun the Plain of Jars to within ten kilometers of the guerrillas' main base at Long Chieng. As a riposte, Hmong General Vang Pao plotted another spoiling offensive against the pressing communists. However, the People's Army of Vietnam (PAVN) beat him to it with Campaign Thoan Thang. After the Vietnamese campaign ran its course, Vang Pao launched yet another inconclusive offensive that failed to clear the foe from the Plain of Jars, Operation Off Balance. By 28 June 1969, the PAVN had 60 tanks deployed. Additionally, there were seven new Vietnamese infantry battalions poised on the Plain, while the Royalist remained unreinforced. The PAVN now had a total of 26 battalions in the Plain of Jars area, seemingly poised for a further wet season offensive.