1954 First Indochina War: The Geneva Conference partitions Vietnam into North Vietnam and South Vietnam.
1954 Dwight D. Eisenhower pledges United States support to South Vietnam
1955 Operation Passage to Freedom, the evacuation of 310,000 Vietnamese civilians, soldiers and non-Vietnamese members of the French Army from communist North Vietnam to South Vietnam following the end of the First Indochina War, ends.
1955 Ngô Đình Diệm declares himself Premier of South Vietnam.
1957 Ngo Dinh Diem of South Vietnam survived a communist shooting assassination attempt in Ban Me Thuot.
1957 President Ngo Dinh Diem of South Vietnam becomes the first foreign head of state to make a state visit to Australia.
1958 A parcel bomb sent by Ngo Dinh Nhu, younger brother and chief adviser of South Vietnamese President Ngo Dinh Diem, fails to kill King Norodom Sihanouk of Cambodia.
1960 A military coup against President Ngo Dinh Diem of South Vietnam is crushed.
1961 United States President John F. Kennedy sends 18,000 military advisors to South Vietnam.
1963 A protest against pro-Catholic discrimination during the Buddhist crisis is held outside South Vietnam's National Assembly, the first open demonstration during the eight-year rule of Ngo Dinh Diem.
1963 The Buddhist crisis: Soldiers of the Army of the Republic of Vietnam attack protesting Buddhists in Huế, South Vietnam, with liquid chemicals from tear gas grenades, causing 67 people to be hospitalised for blistering of the skin and respiratory ailments.
1963 Buddhist monk Thich Quang Duc burns himself with gasoline in a busy Saigon intersection to protest the lack of religious freedom in South Vietnam.
1963 South Vietnamese President Ngô Ðình Diệm is assassinated following a military coup.
1963 Vietnam War: Following the November 1 coup and execution of President Ngo Dinh Diem, coup leader General Duong Van Minh takes over leadership of South Vietnam.
1963 Vietnam War: Newly sworn-in US President Lyndon B. Johnson confirms that the United States intends to continue supporting South Vietnam both militarily and economically.
1964 Vietnam War: at a rally in Saigon, South Vietnamese Prime Minister Nguyen Khanh calls for expanding the war into North Vietnam.
1964 Vietnam War: Viet Cong forces attack the capital of Dinh Tuong Province, Cai Be, killing 11 South Vietnamese military personnel and 40 civilians (30 of which are children).
1964 Vietnam War: 5,000 more American military advisers are sent to South Vietnam bringing the total number of United States forces in Vietnam to 21,000.
1964 Vietnam War: A ''coup d'état'' replaces Duong Van Minh with General Nguyen Khanh as President of South Vietnam. A new constitution is established with aid from the U.S. Embassy.
1964 North Vietnamese Army begins infiltration of South Vietnam.
1965 Vietnam War: The first United States combat troops are sent to South Vietnam.
1965 Vietnam War: American warships begin the first bombardment of National Liberation Front targets within South Vietnam.
1965 Civilian Prime Minister of South Vietnam Phan Huy Quat resigned after being unable to work with a junta led by Nguyen Cao Ky.
1965 Nguyen Cao Ky became Prime Minister of South Vietnam at the head of a military junta; General Nguyen Van Thieu became the figurehead chief of state.
1965 Vietnam War: The United States uses B-52 bombers to attack National Liberation Front guerrilla fighters in South Vietnam.
1965 Vietnam War: U.S. President Lyndon B. Johnson announces his order to increase the number of United States troops in South Vietnam from 75,000 to 125,000.
1965 Vietnam War: In a follow-up to August's Operation Starlight, United States Marines and South Vietnamese forces initiate Operation Piranha on the Batangan Peninsula.
1965 Vietnam War: The 1st Cavalry Division (United States) (Airmobile), in conjunction with South Vietnamese forces, launches a new operation seeking to destroy North Vietnamese forces in Pleiku in the II Corps Tactical Zone (the Central Highlands).
1965 Vietnam War: In response to U.S. President Lyndon B. Johnson's call for "more flags" in Vietnam, Philippines President Elect Ferdinand Marcos announces he will send troops to help fight in South Vietnam.
1966 Lyndon B. Johnson states that the United States should stay in South Vietnam until Communist aggression there is ended.
1966 Military Prime Minister of South Vietnam Nguyen Cao Ky sacked rival General Nguyen Chanh Thi, precipitating large-scale civil and military dissension in parts of the nation.
1966 After a policy dispute, Prime Minister Nguyen Cao Ky of South Vietnam's ruling junta launches a military attack on the forces of General Ton That Dinh, forcing him to abandon his command.
1966 A Canadair CL-44 chartered by the United States military crashes into a small village in South Vietnam, killing 129.
1967 Vietnam War: US and South Vietnamese forces engage Viet Cong troops in the Mekong Delta.
1968 Operation Igloo White, a US electronic surveillance system to stop communist infiltration into South Vietnam begins installation.
1968 Vietnam War: The Tet Offensive begins when Viet Cong forces launch a series of surprise attacks in South Vietnam.
1968 Vietnam War: The execution of Viet Cong officer Nguyen Van Lem by South Vietnamese National Police Chief Nguyen Ngoc Loan is videotaped and photographed by Eddie Adams. This image helped build opposition to the Vietnam War.
1968 Vietnam War: The Tet Offensive is halted; South Vietnam recaptures Hué.
1968 Vietnam War: South Vietnamese opposition leader Trương Đình Dzũ is sentenced to five years hard labor for advocating the formation of a coalition government as a way to move toward an end to the war.
1968 Vietnam War: Operation Commando Hunt initiated. The goal is to interdict men and supplies on the Ho Chi Minh Trail, through Laos into South Vietnam.
1969 The United States begins secretly bombing the Sihanouk Trail in Cambodia, used by communist forces to infiltrate South Vietnam.
1969 Melbourne-Evans collision: Off the coast of South Vietnam, the Australian aircraft carrier {{HMAS|Melbourne|R21|6}} cuts the U.S. Navy destroyer {{USS|Frank E. Evans|DD-754|6}} in half.
1969 Vietnam War: US President Richard M. Nixon makes an unscheduled visit to South Vietnam and meets with President Nguyễn Văn Thiệu and U.S. military commanders.
1970 During the Cambodian Civil War, massacres of the Vietnamese minority results in 800 bodies flowing down the Mekong River into South Vietnam.
1970 Vietnam War: United States and South Vietnamese forces invade Cambodia to hunt Viet Cong.
1970 Vietnam War: Operation Jefferson Glenn begins: the United States 101st Airborne Division and the South Vietnamese 1st Infantry Division initiate a new operation in Thừa Thiên-Huế Province.
1971 Vietnam War: Backed by American air and artillery support, South Vietnamese troops invade Laos.
1972 Vietnam War: The Easter Offensive begins after North Vietnamese forces cross into the Demilitarized Zone (DMZ) of South Vietnam.
1972 Vietnam War: Nguyen Hue Offensive – The North Vietnamese 320th Division forces 5,000 South Vietnamese troops to retreat and traps about 2,500 others northwest of Kontum.
1972 Vietnam War: the last United States ground combat unit departs South Vietnam.
1972 Vietnam War: In Saigon, Henry Kissinger and South Vietnamese President Nguyen Van Thieu meet to discuss a proposed cease-fire that had been worked out between Americans and North Vietnamese in Paris.
1973 Vietnam War: The last United States combat soldiers leave South Vietnam.
1974 Vietnam War: the U.S. Congress places a $1 billion dollar limit on military aid to South Vietnam.
1975 Vietnam War: North Vietnamese troops attack Ban Me Thuot, South Vietnam, on their way to capturing Saigon.
1975 Vietnam War: President of South Vietnam Nguyen Van Thieu flees Saigon, as Xuan Loc, the last South Vietnamese outpost blocking a direct North Vietnamese assault on Saigon, falls.
1975 As North Vietnamese forces close in on the South Vietnamese capital Saigon, the Australian Embassy is closed and evacuated, almost ten years to the day since the first Australian troop commitment to South Vietnam.
1975 As North Vietnamese forces close in on the South Vietnamese capital Saigon, the Australian Embassy is closed and evacuated, almost ten years to the day since the first Australian troop commitment to South Vietnam.
1975 Fall of Saigon (or Liberation of Saigon from the Communist perspective): Communist forces gain control of Saigon. The Vietnam War formally ends with the unconditional surrender of South Vietnamese president Duong Van Minh.
1976 Fall of the Republic of Vietnam; Communist North Vietnam declares their union to form the Socialist Republic of Vietnam.