 At 03 : 00 on 31 January North Vietnamese forces assailed Saigon , Cholon , and Gia Định in the Capital Military District ; Quảng Trị ( again ) , Huế , Quảng Tín , Tam Kỳ , and Quảng Ngãi as well as U.S. bases at Phú <unk> and Chu Lai in I Corps ; Phan Thiết , Tuy Hòa , and U.S. installations at Bong Son and An Khê in II Corps ; and Cần Thơ and Vĩnh Long in IV Corps . The following day , Biên Hòa , Long Thanh , Bình Dương in III Corps and Kien Hoa , Dinh Tuong , Gò Công , Kiên Giang , Vĩnh Bình , Bến Tre , and Kien Tuong in IV Corps were assaulted . The last attack of the initial operation was launched against <unk> <unk> in IV Corps on 10 February . A total of approximately 84 @,@ 000 Viet Cong and North Vietnamese troops participated in the attacks while thousands of others stood by to act as reinforcements or as blocking forces . Viet Cong and North Vietnamese forces also mortared or rocketed every major allied airfield and attacked 64 district capitals and scores of smaller towns . 
