Fifty thousand U.S. troops landed on the coast of Okinawa, an island in Japan, on this day in 1945. It was the beginning of the deadliest battle in the course of the Pacific War. It would last for nearly three months and would cost the lives of shocking numbers of people. About 95,000 Japanese troops and over 20,000 U.S. troops lost their lives just during the ground battle, without even counting the air and naval components of the conflict. An official memorial states that nearly 150,000 civilians died during the fighting, around a quarter of the island's population.
The U.S. forces made landfall after a fierce naval battle. In response, 1,900 Japanese kamikaze attacks struck ground and naval forces, continuing until the U.S. was able to set up an air defense system. But it was the ground fighting that drew the most blood. Japanese troops holed up in caves across the island, creating a treacherous landscape for any Americans trying to take territory. They'd also mined and pre-targeted much of the land for artillery fire. Still, over time the Japanese troops were weakened by attrition. Defense line after defense line was crossed until the writing was on the wall: the U.S. would take the island.
The commanders of both sides would be dead by the end of the fighting. U.S. Army Lieutenant General Simon Buckner, Jr., was killed by artillery fire as combat was nearing its end, marking the death of the highest-ranking U.S. military officer during the war. Japanese Army General Mitsuru Ushijima committed ritual suicide for his failure as a form of apology to the emperor of Japan. The Allied victory meant the U.S. had a useful location from which to stage the invasion of the Japanese home islands. That invasion would never come: Japan surrendered before the invasion was mounted.
For more on the Battle for Okinawa, check out this article from the National WWII Museum.