Liberation of Guam: Operation Forager & the Battle for the Mariana Islands

Context: The Mariana Campaign

Guam, a US territory since 1898, was seized by Japan on December 10, 1941. Its recapture was essential for B-29 bases to strike Japan and cutting Japanese supply lines.

Operation Forager (June–August 1944)

Simultaneous assaults on Saipan (June 15), Guam (July 21), Tinian (July 24).

Guam Assault: July 21 – August 10, 1944

• Command: III Amphibious Corps (Geiger) — 3rd MarDiv, 1st ProvMarBde, 77th InfDiv. ~55,000 troops.
• Deception: Feint at Tumon Bay (north); main landing at Asan & Agat Beaches (west).
• Japanese Defense: ~19,000 (Takashina) — entrenched in limestone cliffs, caves, pillboxes (Fonte Plateau, Mt. Santa Rosa).
• Key Phases:
  1. Beachhead (Jul 21–24): Heavy casualties securing reefs/beaches; tanks decisive.
  2. Cut the Island (Jul 24–28): 3rd MarDiv drove across waist to east coast, isolating north.
  3. North (Jul 28–Aug 10): Brutal cave/clearing fighting (Fonte, Mt. Santa Rosa, Ritidian).
  4. South (Jul 21–Aug 10): 77th InfDiv cleared Orote Peninsula, Apra Harbor.
• Declared Secure: August 10 (mopping up continued to Oct).

Human Cost

• US: 1,783 killed, 6,010 wounded.
• Japanese: ~18,500 killed, 1,250 captured.
• CHamoru: ~1,000 killed; 10,000–15,000 interned in concentration camps (Manengon, Asinan) — starvation, forced labor, execution. Endured 31 months occupation.

Aftermath

• Apra Harbor → major naval base; Andersen AFB (B-29s) built.
• CHamoru loyalty to US cemented; Organic Act 1950 granted citizenship, civilian gov.
• War in the Pacific NHP (Asan Beach, Asan Bay Overlook, Fonte Plateau) preserves sites.