My father was a Navy corpsman. He served on the USS New Orleans, which was torpedoed (150 feet of bow blown completely away) during the Battle of Tassafaronga.
photo:
http://www.navsource.org/archives/04/0403205.jpg
They were trying to intercept Japanese resupply of Guadacanal.
With the ship out of action, he was assigned to a hospital unit on Tulagi. Eventually he came down with malaria and was returned to the states for care.
His next assignment was to the 28th Regiment of the the 5th Marine Division. He landed in the first wave on green beach at the base of Mt. Suribachi, and was wounded on the first day by shrapnel to the head, shoulder, chest, and knee. He still sets off metal detectors at airports. He stayed with his platoon until the very last day of the battle up in the gorges on the far side of the island from Suribachi. He was decorated for gallantry and wounds (Silver Star and Purple Heart.)
Iwo Jima was essentially an underground fortress. General Kuribayashi and his staff devised a defensive system intended to fight intelligently for every square foot of the island. Spotters flying above the battle said the Marines were like a beehive of activity, but when they flew over the Japanese positions they saw almost nothing. They were in thousands of caves and heavily fortified bunkers, and much of it was interconnected by underground tunnels. They knew exactly what they could hit, and knew exactly how to hit it. There were very few undisciplined and fruitless charges of massed troops. It was a defense designed to fight from positions of strength to the very last man.
19,733 Marines died in WWII - roughly 7000 of them died during one month on Iwo Jima.
I don't know which was worse, but the defense of Iwo Jima was both brilliant and lethal.