. >> smith relied heavily on 38-year-old colonel david shoop. job was to mastermind the assault on how and when to attack the japanese. but first, he had to figure out how many there were and he did in it an unusual way. >> they found out how many men were defending by how many la treens there were. really? >> the small structures built over the water mean here are la treens. >> you can count theetoilet seats and figured an officer a seat to himself and a troop probably have to share maybe four or five of them. 4.5 to a toilet seat and came up with a total count of 4,400 people on the island and they were off by about 6 men. >> the island was surrounded by a treacherous coral reef out approximately 1,000 yards. known as amtraks to clear the reef rrgardless of the tide. >> they ran with these deep cleats. when they ncountered the reef they went over. >> they relied on returning lvts to transport them in if thhy were stuck but the japanese had turned the entire island into a fortress. what did they put into tarawa to defend it? >> they bruought in