Page "Flag of South Vietnam" Paragraph 6

After the deportation and exile of the Emperors Thành Thái and Duy Tân, the new pro-French ruler Khải Định chose to change the imperial flag, replacing the three strips which signified the three regions of Vietnam ( North, Central, and South ) with a single horizontal band of red.

Formally known as the " Long Tinh ", the flag was the official flag of the Nguyễn Court.