sentences:  On the evening of May 2, 1975, the rebel prisoners on Côn Đảo Island successfully establish communications with North Vietnamese military units.To prepare for the arrival of the North Vietnamese, the Provisional Committee moved to set up a trench system around the island to defend against a possible South Vietnamese or U.S. counter-attack.On the morning of May 5, 1975, the North Vietnamese 171st and 172nd Naval Regiments landed on Côn Đảo Island with elements of the PAVN 3rd Division.