The Battle for Saigon was a month-long battle between the Vietnamese National Army of the State of Vietnam and the private army of the Binh Xuyen organised crime syndicate. At the time, the Binh Xuyen was licensed with controlling the national police by Emperor Bảo Đại, and Prime Minister Ngo Dinh Diem issued an ultimatum for them to surrender and come under state control. The battle started on April 27, 1955 and the VNA had largely crushed the Binh Xuyen within a week.