 His forces were shattered at the Battle of An Lộc, where he threw several divisions at the entrenched South Vietnamese forces, ultimately losing over half of his army as casualties.General Giap's loss and subsequent retreat was viewed as so great a failure by the North Vietnamese Communist Party that Giap was relieved of his command.Although ARVN troops withstood and repelled the massive PAVN attack at An Lộc, American air power seems to have been a key to the ARVN success, just as it had been a key factor in supporting U.S. ground forces when they operated in South Vietnam prior to 1972.