The fall of Huế to PAVN forces on 26 March 1975 began an organized rout of the ARVN that culminated in the complete disintegration of the South Vietnamese government. Withdrawing ARVN forces found the roads choked with refugees making troop movement almost impossible. North Vietnamese forces took advantage of the growing instability, and with the abandoned equipment of the routing ARVN, they mounted heavy attacks on all fronts. With collapse all but inevitable, many ARVN generals abandoned their troops to fend for themselves and ARVN soldiers deserted "en masse". The 18th Division held out at Xuân Lộc from 9 to 21 April before being forced to withdraw. President Thiệu resigned his office on 21 April and left the country. At Bien Hoa, ARVN soldiers made a strong resistance against PAVN forces, however, ARVN defenses at Cu Chi and Hoc Mon start to collapse under the overwhelming PAVN attacks. In the Mekong Delta and Phu Quoc Island, many of ARVN soldiers were aggressive and intact to prevent VC taking over any provincial capitals. Less than a month after Huế, Saigon fell and South Vietnam ceased to exist as a political entity. The sudden and complete destruction of the ARVN shocked the world. Even their opponents were surprised at how quickly South Vietnam collapsed.