sentences:  Within a few hours of the agreement, the 5th Division crossed the border at three places, closed in on the railhead, and the Battle of Lang Son ensued.Vichy France protested the breach of the agreement on September 23, but the Indochina Expeditionary Army, supported by the Imperial Japanese Navy, began sorties on the following morning on Haiphong in the Gulf of Tonkin.Japanese forces landed on September 26, and captured the city of Hanoi by evening.