Claim: Reunification Day also known as the “Fall of Saigon” in the overseas Vietnamese community took place on July 2, 1976, when the Republic of South Vietnam (headed by Nguyễn Hữu Thọ) and North Vietnam, merged the two independent countries, forming modern-day Vietnam.
Evidence: Reunification Day (Vietnamese: Ngày Thống nhất), Victory Day (Ngày Chiến thắng), Liberation Day (Ngày Giải phóng or Ngày Giải phóng miền Nam), or the official name Day of Southern Liberation for National Reunification (Giải phóng miền Nam, thống nhất đất nước) is a public holiday in Vietnam that marks the event when North Vietnamese and Việt Cộng forces captured Saigon (now Ho Chi Minh City) on April 30, 1975. It was the start of the transition period toward reunification, which occurred in the national election for national reunification on July 2, 1976, when the Republic of South Vietnam and North Vietnam merged the two independent countries, forming the modern-day Vietnam. In the Overseas Vietnamese community, the day is remembered as the "Fall of Saigon", "Black April" (Tháng Tư Đen), "National Day of Shame" (Ngày Quốc Nhục) or "National Day of Hate" (Ngày Quốc Hận). Day of liberating the South for national reunification (Giải phóng miền Nam, thống nhất đất nước) Reunification Day (Ngày Thống nhất)
Liberation Day (Ngày Giải phóng)
Victory Day (Ngày Chiến thắng)
Black April (Tháng Tư Đen)
Fall of Saigon (Sài Gòn Thất thủ) Vietnamese National Marks the liberation of the South for national reunification Fall of Saigon 
The Fall of Saigon, also known as the Liberation of Saigon, was the capture of Saigon, the capital of South Vietnam, by the People's Army of Vietnam (PAVN) and the Viet Cong on 30 April 1975. The event marked the end of the Vietnam War and the start of a transition period to the formal reunification of Vietnam into the Socialist Republic of Vietnam. 
Nguyễn Hữu Thọ (10 July 1910 – 24 December 1996) was a Vietnamese revolutionary and Chairman of Consultative Council of the National Liberation Front of South Vietnam from 6 June 1969 to 2 July 1976, and the Chairman of the National Assembly of Vietnam from 4 July 1981 to 18 June 1987. After his escape, he was first interim president and then chairman of the National Front for the Liberation of South Vietnam, which was co-founded by him on December 20, 1960 (Mặt Trận Giải Phóng Miền Nam Việt Nam,). With this liberation movement he carried out successful protests against the government of South Vietnam. During the Vietnam War, the NLF founded the Provisional Revolutionary Government of South Vietnam in June 1969, in which Huỳnh Tấn Phát became President and he himself became Chairman of the Consultative Council. After the conquest of Saigon by a unit of the North Vietnamese Army and the Viet Cong in April 1975, he became Prime Minister of South Vietnam. After the reunification and the founding of the Socialist Republic of Vietnam on 2 July 1976, he was one of two vice-presidents and thus deputy of Tôn Đức Thắng. At the same time he was the first mayor of Ho Chi Minh City.