On 12 January, the Marines began their advance with the 8th Marines along the shore and 2d Marines inland. All along the front of the advancing assault companies the going was rough. The Japanese, remnants of the Sendai Division, were dug into the sides of a series of cross compartments and their fire took the Marines in the flank as they advanced. Progress was slow despite massive artillery support and naval gunfire from four destroyers offshore. In two days of heavy fighting, flamethrowers were employed for the first time and tanks were brought into play.