If the United States could take the island, they would eliminate that threat, provide an emergency landing field for damaged bombers, and eventually put fighter aircraft close enough to Japan to escort the B-29s over the target.

The price of taking it would be terrible.

The island’s volcanic terrain — black sand beaches, rocky ridges, tunnels and caves carved into the volcanic rock by tens of thousands of Japanese defenders who had spent months preparing — made it one of the most fortified pieces of land in the Pacific.

General Tadamichi Kuribayashi, commanding the Japanese garrison of approximately 21,000 men, knew that the island would be attacked.

He designed a defense intended not to repel the invasion at the beaches — a conventional defense that air and naval bombardment had proven could be defeated — but to draw the attackers inland into a maze of interlocking positions from which every approach was covered by fire.