The Guam landings had been tentatively set for 18 June but a large Japanese carrier attack and stubborn resistance by the unexpectedly large Japanese garrison on Saipan led to the invasion of Guam being postponed for a month.
Since the Marianas lie in the Central Pacific, their capture was the responsibility of the U.S. Fifth Fleet, led by Vice Admiral Raymond A. Spruance from aboard his flagship, heavy cruiser Indianapolis.
The ships and embarked troops of both Operation Forager I, for the Central Marianas (Saipan and Tinian) and Forager II, for the Southern Marianas (Guam), were under the overall command of Rear Admiral Richmond Kelly Turner aboard amphibious command ship Rocky Mount.
The Marine and Army landing forces for both the Central and Southern Marianas phases of Operation Forager were under the overall command of Maj. Gen. Holland M. "Howlin' Mad" Smith, USMC.
III Marine Amphibious Corps (Maj. Gen. Roy S. Geiger, USMC) Lieutenant General Holland M. Smith[a] III Marine Amphibious Corps Major General Roy S. Geiger[c] Overall command[3] Lt. Gen. Takeshi Takashina (KIA 28 July)