Yet for the Amphib landing on Okinawa, both Marines and Army units served at the point of the combat arms effort.
They fought and died alike as infantrymen. And for that we can all be proud and grateful for them.
Yet the greatest loss of life at Okinawa was by Navy troops from Kamakazi attacks.
"The United States created the Tenth Army, a cross-branch force consisting of the 7th, 27th, 77th, and 96th infantry divisions of the US Army with the 1st, 2nd, and 6th divisions of the Marine Corps, to fight on the island. The Tenth was unique in that it had its own tactical air force (joint Army-Marine command), and was also supported by combined naval and amphibious forces."
(How we fought wwhen we intended total victory, and got it; not hearts and minds, half measures strategies used since then, with incomplete wars-Korea, Vietnam, Afghanistan, Iraq)
https://en.wikipedia.org/wiki/Battle_of_Okinawa