Question

why was it difficult to invade Iwo Jima

Answer 1

http://www.history.com/topics/world-war-ii/battle-of-iwo-jima

Answer 2

There are a lot of reasons, but mainly it was that the Japanese were ready.

They had time to become well entrenched on the island with massive fortifications, tunnels, and a system of defenses in place. Most of them had also fought to the death. Out of the 22,000 or so Japanese soldiers on the island, only around 200 were left alive at the end.

Answer 3

I have a friend who was there. He just turned 89. The invasion happened on his birthday. He tells a great story about it/ But yeah, @Captain_Page_Turner is right.