Operation Phou Phiang II (6 August – 25 October 1972) was one of the final battles of the Laotian Civil War. It was an attempt to relieve the siege on the guerrilla headquarters at Long Tieng on the Plain of Jars. It was designed as a two phase attack consisting of five task forces of Thai mercenaries and Royalist guerrillas upon the People's Army of Vietnam invading Laos. Air superiority was used to direct over 100 air strike sorties daily to support the offense, and air mobility to shuffle attacking troops. A new radar bombing program by F-111 Aardvarks and B-52 Stratofortresses failed to cripple the Communist forces. Designed to overwhelm Communist defenses with its multiplicity, the five Lao task forces were defeated in detail by the Communists despite two new columns being improvised