While a member of the leadership of the UBCV, Thích Quảng Độ became an activist, fighting against the anti-Buddhist policies of the Catholic President of South Vietnam Ngô Đình Diệm. After a military raid of Buddhist monasteries in Hue and Saigon, Thích Quảng Độ was arrested on 20 August 1963. He and thousands of other Buddhists endured torture and persecution while imprisoned by the Diem government. He was released after Diem regime was toppled in military coup in November 1963. As a result of imprisonment, Thích Quảng Độ struggled with tuberculosis before having a lung operation in Japan in 1966.