Which battle was the largest all-Marine force and was the bloodiest in USMC history?

• A. Iwo Jima
• B. Belleau Wood
• C. Guadalcanal
• D. Tarawa

Answer: (D)

Tarawa captures a pivotal moment when Marines faced an immense, all-Marine landing under intense opposition and paid a heavy price in the effort to secure an island in the Pacific. The battle, fought at Betio in the Gilbert Islands in November 1943, involved roughly twelve thousand Marines landing in a single operation—the largest all-Marine force to assault an island up to that point. The assault faced brutal and well-fortified Japanese defenses, and the infamous reef and shallow water prevented many landing craft from reaching shore, forcing troops to wade ashore under withering fire. That chaotic, close-quarters fight on the beaches and through the island’s defenses led to very high Marine casualties in a short period, cementing Tarawa as the bloodiest battle for the Marine Corps in its history at that time.

While later battles like Iwo Jima would involve more Marines and inflict even heavier total losses, Tarawa stands out for the combination of a large, all-Marine landing force and the extreme intensity and cost of the beach assault, which is why it stands out as the best fit for this question.