Answer: Hue
The Battle of Hue (or Massacre of Hue) is considered one of the bloodiest events of the war. It started on January 31, 1968 and lasted for 26 days. During the capture and occupation of the city by the Viet Cong and the People's Army of Vietnam, a huge amount of executions and mass killings took place. The death toll is estimated to be between 2,800 and 6,000 civilians and POWs.