Your uncle , Second Lieutenant Glenn Sayre, U.S.Marine Corps, 2nd. Marine Division, died on the first day of the invasion of Saipan by an amphibious assault headed by Vice Admiral R Kelly Turner. Major General Holland "Howlin Mad" Smith commanded the 2nd MD and 4th MD during this encounter.
The huge amphibious fleet appeared off Saipan, carrying the 2nd MD and 4th MD, plus one reserve regiment. They were going against a Japanese force in excess of 30,000 troops, led by the infamous Vice-Admiral Nagumo.
A heavy bombardment began at 5:45AM, with the first 700 landing craft of the Marines headed for shore at 8:40 AM, landing on the west coast of Saipan.
The 2nd. division landed north of Point Afetna, while the 4th. landed south of it. All of this under intense fire from the Japanese.
A tactical error resulted in the 2nd. division landing further north than ordered, with the result that there was an unexpected gap between the two divisions, leaving both units open to flank attack.
The Japanese sought to drive the Americans back into the sea by night attack, but were unsuccessful. Both sides experienced heavy casualties.
Mopping up of the southern part of the island was finished 30 June 44, with the invasion of Guam next on the schedule for the 2nd & 4th MD, plus 27th Infantry Division and 77th. Infantry Division, just arrived from Hawaii.
Which completes the history for the date of Glenn's death.
If you haven't seen it, he is memorialized as follows:
Glenn William Sayre Second Lieutenant, U.S.Marine Corps S/N O-027613 United States Narine Corps Entered the Service from: California Died : June 15, 1943 Missing in Action or Buried at Sea Tablets of the Missing at Honolulu Memorial Honolulu
Awards : Purple Heart
I have visited this cemetery several times, and it is beautiful and inspirational.
So there appears to be credence to the family belief that he was victim of an attack at sea as he was being transported to a hospital ship.