What was the name of the main Island on Tarawa Atoll the U.S attacked?

Question

and why did they have so many casualties?

Answer 1

1.  Betio.

2.  Multiple reasons:

--the Japanese were dug-in.

--More importantly, while we'd captured many islands to this point (Guadalcanal, New Guinea for instance), this was the FIRST island where the japanese contested the amphibious landing.  Up to this point, we either went ashore unopposed or to light fire and the major engagements took place further inland.  But not this time--the beach had entrenched troops in numbers with interlocking fields of fire determined not to give ground.

--No cover (other than the sea-wall)

--We falsely assumed that the bombardment (especially since Betio was so small) wiped out most of the garrison so the combination of being cocky and also unprepared for this was a kick in the nuts.

--Yeah, our tidal maps were off.  But it's also an atoll.  It's surrounded by a coral reef.  We assumed we'd have 5 feet of water over the reef and it turned out we only had 3--frankly I think many of the landing craft still would have gotten stuck on the reef.  So most of the troops didn't land on the shore.  They landed on the reef and had to walk ashore in the water.  It wasn't rough surf but it was anywhere from 200-500 yards off-shore.  Imagine wading through 3 feet of water, under fire for 500 yards with no place to hide or get cover.

--Most of our tanks and amtracs were disabled the first day and they were the only means we had of getting across the coral (other than walking).

--infiltration.  Many of the japanese dugouts were inter-linked.  We'd take one out, move on and then Japanese would pop back out (via a connecting tunnel) and open fire.  There was a disabled freighter off a dock that we bypassed and it turned out to hold several Japanese snipers.  Another Japanese marine swam out to a disabled Amtrac hung up on the reef and used it's .50 cal. to open up on the reef of the forces on the beach--stuff like that.

--refusal to surrender.  My understanding is that we captured few prisoners and almost all of them were Korean laborers, not japanese military.   The count I have seen said 24 Japanese POWs (and 100+ Korean laborers) captured with most of the Japanese being wounded or disabled in some manner.

Answer 2

Betio Island.

The Japanese were very well entrenched:

http://www.lonesentry.com/articles/jp-be...

Also, the Allies lacked accurate charts, causing many landing craft to run aground. There were several slip-ups in timing which meant that the attack was badly coordinated.

http://history.sandiego.edu/gen/ww2Timel...

Answer 3

agility man covers it well

Answer 4

Additionally Tarawa is in the Gilbert Island chain, which is now

part of Kiribati.