[2] Định was born from a peasant family in Bến Tre Province, and fought with the Viet Minh forces against the French.

She was arrested and incarcerated by the French colonial authority between 1940–43, and helped lead an insurrection in Bến Tre in 1945, and again in 1960 (against the government of Ngô Đình Diệm).

In 1965 she was elected chairwoman of the South Vietnam Women's Liberation Association, who were given the name the "long-haired warriors" by Ho Chi Minh.

Together with Madame Nguyễn Thị Bình, she is one of the two most prominent female Vietnamese communist leaders.

[5] Định was interviewed by Stanley Karnow for Vietnam: A Television History documentary.