In order to clear Japanese forces in between the site of the planned new base on the Marshall Islands and Hawaii, the heavily fortified airbase on Betio Island in the Tarawa Atoll needed to be destroyed. Betio was defended by 4,500 Japanese soldiers and an array of heavy fortifications and guns which mainly faced the open water away from the lagoon. The Americans attacked with the full force of the Pacific fleet’s capabilities and had 35,000 troops ready to go ashore at a number of different locations. The tide on the day of the initial attack left the troop landing vessels stranded in the lagoon, resulting in mass casualties as the Japanese guns easily picked them off. Heavy naval artillery bombardment and air attacks pulverized the Japanese defences but it still took two days to fully secure Betio, resulting in 896 American deaths and just 17 Japanese survivors.