HistoryData
Historical ConflictBougainville Island

Battle of Koromokina Lagoon

A Japanese counter-landing on Bougainville was repulsed, securing the Allied beachhead and enabling construction of airfields to neutralize Rabaul.

Duration & Scope

1943 ongoing

< 1 year

Key Facts

Dates
7–8 November 1943
Japanese assault force
850 soldiers
Transport vessels
4 destroyers
U.S. units engaged
Two battalions, 3rd and 9th Marine Regiments
Campaign context
Bougainville campaign, Pacific War

Strategic Narrative Overview

On the night of 7 November 1943, Japanese forces landed from four destroyers near Koromokina Lagoon and attacked positions held by two battalions of the 3rd and 9th Marine Regiments under Major General Allen H. Turnage. Over two days of fighting, the Marines repelled each Japanese assault. The attackers suffered heavy losses and failed to penetrate the defensive perimeter.

01 / The Origins

Following the Allied amphibious landing at Cape Torokina on Bougainville in November 1943, Japanese General Hitoshi Imamura, commanding the 8th Area Army at Rabaul, ordered an immediate counterattack. Underestimating Allied strength ashore, he dispatched 850 troops by destroyer to execute a counter-landing near Koromokina Lagoon, intending to drive the Marines back into the sea before the beachhead could be consolidated.

03 / The Outcome

The Japanese counter-landing force was defeated with heavy casualties, ending the immediate threat to the Cape Torokina beachhead. With the perimeter secured, Allied forces proceeded to expand their foothold on Bougainville, ultimately constructing airfields from which they could attack and neutralize Japanese installations at Rabaul and surrounding areas.

Belligerents & Mobilization Analysis

Side A

1 belligerent

Imperial Japanese Army
Peak Mobilized Forces850
Forces vs Casualties ratio
0Mobilized
Key Commanders

Hitoshi Imamura.

Side B

1 belligerent

United States Marine Corps
Key Commanders

Allen H. Turnage.

Outcome
U.S. Marine victory; Japanese counter-landing repulsed with heavy losses; Allied beachhead at Cape Torokina secured

Kinetic Engagement Axis

Major engagements timeline (1943–present)Timeline of major military engagements plotted chronologically.1943present1943Battle of Koromo…Side B

Scroll horizontally to view full axis. Events plotted relatively.

Side A victorySide B victoryInconclusiveDecisive / turning point

Location

Map of Papua New GuineaMap of Papua New GuineaPapua New Guinea