Black smoke covered the island, and shrapnel was flying all over the place with a shrieking sound. Trees with trunks one meter across were blown out of the ground, roots uppermost. The sound was deafening, as terrible as a couple of hundred thunderclaps coming down at once. Even in a cave thirty meters underground, my body was jerked up off the ground. It was hell on earth.

The US forces in the Pacific now moved onto another staging post on the route to the Japanese mainland. Iwo Jima was half-way between the Mariana islands, already in US hands, and Japan itself. Capturing it would prevent it being used by the Japanese to spot or intercept bombers en route to Japan and would halve the distance the US bombers needed to fly. The initial assessment was that it could be captured relatively easily.

On the 16th February 1945 Marine Brigadier General William W. Rogers held a press conference on the command ship USS Eldorado, telling those present that the coming invasion of Iwo Jima would take five days. Strong fighting on the beaches was expected followed by counter-attacks at night – suicidal Banzai charges. But once the initial resistance was over they could take the island quickly.

There were reasons to believe that the Japanese forces on Iwo Jima were seriously weakened, they had been subject to bombing since mid 1944, and they had been bombed every single day for the past 74 days, with a total of 6,800 tons of bombs. In addition there had been periodic, intense, naval bombardments, which started again on the 16th.

It seemed hard to believe that anything could survive on the island after this plastering – but the raids had served to encourage the Japanese in their new strategy of moving underground and waiting for the invasion troops to come to them.

Takahashi Toshiharu was a corporal in the Japanese First Mixed Brigade of Engineers, responsible for building some of the eleven miles of tunnels and underground bunkers on the island:

The guns that were trained on the island all spurted fire at the same time. On the island there was a huge earthquake. There were pillars of fire that looked as if they would touch the sky. Black smoke covered the island, and shrapnel was flying all over the place with a shrieking sound. Trees with trunks one meter across were blown out of the ground, roots uppermost. The sound was deafening, as terrible as a couple of hundred thunderclaps coming down at once. Even in a cave thirty meters underground, my body was jerked up off the ground. It was hell on earth. … Next, large planes—many tens of them—came all together. They made a deep rumbling sound as they came. They were silver. Once over the island they dropped one-ton bombs — terrifying things. The sound they made as they fell, one after another, was terrifying. A timid man would go insane. They made a whistling sound as they fell. Then the earth shook. There were explosions. Rocks, earth, and sand all flew up into the air. Then they fell back down. They made craters ten meters wide and five meters deep in the earth. No one could survive in these conditions. Any Japanese soldiers, like the runners who went outside, were all killed. The only option was to take advantage of the night and go out then.

See Kumiko Kakehashi: Letters from Iwo Jima: The Japanese Eyewitness Stories That Inspired Clint Eastwood’s Film

The bombing was so intense that vast quantities of earth were dislodged from the summit of Mount Suribachi, the heighest point on the island was now somewhat lower.