American bombers that were based in marianas, pounded iwo jima from the air in november 1944. this pounding went on for more than days.

For 70 days, the US 7th Air Force dropped 5,800 tons of bombs on the little island

Known for its sulfur, the little island was a major battle ground in the pacific front. The battle was decided upon to detach the capability of Zero fighters and their ability to report back to Tokyo from the little island. at that time the Americans were based in Saipan, which they had won in a previous battle.

These islands/chinampas then provided rich soil for crops with easy access to water. i hope this is correct, im so sorry if its not !