Key Facts
- Dates
- 17 January – 9 February 1945
- Duration
- ~3 weeks of main fighting; skirmishes to 22 February
- Australian unit
- 31st/51st Infantry Battalion, 11th Brigade
- Japanese unit
- 81st Infantry Regiment
- Main assault
- 6 February 1945
- Theatre
- Pacific theatre, Bougainville campaign
Strategic Narrative Overview
Beginning on 17 January 1945, the Australian advance encountered determined resistance along Tsimba Ridge, held by Japanese troops of the 81st Infantry Regiment in roughly equal numbers to the attackers. Progress stalled for three weeks. The main Australian assault was launched on 6 February, applying sustained pressure until the Japanese fully withdrew from the ridge on 9 February, with localised skirmishing in the surrounding area continuing until 22 February.
01 / The Origins
By late 1944, Japanese forces on Bougainville Island had withdrawn northward following a series of engagements in the island's centre, consolidating an enclave on the Bonis Peninsula. Australian forces of the 11th Brigade were tasked with driving north to contain and reduce this pocket, with the 31st/51st Infantry Battalion leading the advance toward the Genga River as part of the broader Allied Bougainville campaign in the Pacific theatre.
03 / The Outcome
With Tsimba Ridge secured, the Australians pressed forward to the next operational objective. The subsequent phase of the campaign focused on taking Ratsua, with the aim of establishing a defensive line across the base of the Bonis Peninsula between Ratsua and Ruri Bay, effectively containing the remaining Japanese garrison in the north of the island.
Belligerents & Mobilization Analysis
Side A
1 belligerent
Side B
1 belligerent
Kinetic Engagement Axis
Scroll horizontally to view full axis. Events plotted relatively.