On 13 March the PAVN increased the pressure on the ARVN units in the Ta Luong area and they were forced to move north and FSB Lolo began receiving increased attacks by fire. On 14 March two United States Marine Corps A-4 Skyhawks accidentally bombed a 1st Division position killing 9 ARVN. On the same day an estimated 200 122mm rockets and 100 152mm artillery rounds hit Lolo killing three ARVN. PAVN anti-aircraft weapons were moved closer to the base and by 15 March it could no longer be resupplied. A withdrawal was begun with the 1st Regiment headquarters and the battalions outside the base moving east, while the 4th Battalion acted as a rearguard. On 17 March the PAVN cornered the 4th Battalion near the Sepon River and in an all-day battle the battalion commander, his deputy and most of the company commanders were killed, the survivors escaped to an area near Route 9. On 18 March 32 survivors of the 4th Battalion were rescued by U.S. helicopters.