Iwo Jima and Okinawa: Death at Japan’s Doorstep | The National WWII Museum | New Orleans

On May 29, 1945, the 1st Marine Division conquered Shuri Castle during the Battle of Okinawa. From the article:

"On April 1, 1945, more than 60,000 soldiers and US Marines of the US Tenth Army stormed ashore at Okinawa, in the final island battle before an anticipated invasion of mainland Japan. After a largely unopposed initial advance, US forces soon encountered a network of Japanese inland defenses. Savage fighting erupted at the island’s southern end. Heavy rains and rugged terrain impeded easy movement, and natural defense positions covered the island. A vicious land, sea, and air battle raged for nearly three months. Like the bloodshed on Iwo Jima, Okinawa’s savagery suggested a terrible death toll could follow in the anticipated invasion of Japan’s home islands.

While US Marines overcame Japanese defenses in northern Okinawa by April 18, opposition in the south proved formidable. The Japanese anchored their defenses at historic Shuri Castle, supported by a series of well-defended high ridges. These defenses, and sporadic Japanese counterattacks, held up the American advance. Finally, under relentless assault by the Tenth Army, Shuri Castle fell on May 29, and US Marines seized the airfield at Naha through an amphibious assault commencing June 4, 1945...

...Victory at Okinawa cost more than 49,000 American casualties, including about 12,000 deaths. Among the dead was the Tenth Army’s commander, Lieutenant General Simon Bolivar Buckner Jr., killed on June 18 by a sniper during the final offensive. He was the highest ranking American general killed in action during World War II. About 90,000 Japanese combatants died in the fighting, but deaths among Okinawan civilians may have reached 150,000."