The M48 saw extensive action with the US military during the Vietnam War. Over 600 Pattons would be deployed with US forces during that war. The initial M48s first landed with the US Marine 1st and 3rd Tank Battalions in 1965, with the 5th Marine Tank Battalion later becoming a back-up/reinforcement unit. The remaining Pattons deployed to South Vietnam were in three US Army battalions, namely the 1-77th Armor near the DMZ (67 M48A2C (23 tanks supplied from US Army Training Center at Fort Knox, and 44 tanks from Letterkenny Army Depot) tanks were used by the 77th Armor from August 1968 to January 1969. These were later replaced with M48A3s), the 1-69th Armor in the Central Highlands of central South Vietnam and the 2-34th Armor positioned near the Mekong Delta. Each battalion consisted of approximately 57 tanks. M48s were also used by Armored Cavalry Squadrons in Vietnam until replaced by M551 Sheridan Armored Reconnaissance Airborne Assault Vehicles (ARAAV) in the Divisional Cavalry Squadrons. M48A3 tanks remained in service with the 11th Armored Cavalry Regiment until the unit was withdrawn from the conflict. The M67A1 flame tank (nicknamed the Zippo) was an M48 variant used in Vietnam. From 1965 to 1968, 120 US M48A3 tanks were written off.