Phnom Penh, the capital of Cambodia, fell to the Khmer Rouge, the Cambodian communists allied to North Vietnam, on 17 April 1975. Communist conquest of Southeast Asia was almost complete. The battle for Xuan Loc, less than 40 miles northeast of Saigon, reached new levels of savagery. Here’s the description of the situation from Last of the Annamese:
“In the tank, he [Chuck Griffin, the protagonist] read the incoming dispatches. The battle for Xuan Loc raged on. Elements of the North Vietnamese 7th Division had joined the 341st in the battle. Liberation Radio urged the populace to rebel against the South Vietnamese government. Chuck pulled together signals intelligence, prisoner interrogation reports, and aerial photography and concluded that the North Vietnamese had set up a corps headquarters in Phuoc Long Province. It commanded four divisions, two of which were dispatched to the battle for Xuan Loc. Two more divisions were moving toward Saigon.
“Then came the word they’d been expecting: Phnom Penh had fallen to the Khmer Rouge, the Cambodian Communists allied to North Vietnam. One more domino down.”