Complex sentence: The barge depot around Horaniu was captured by US forces, and by early October 1943, only 600 Japanese soldiers remained, hemmed into a small pocket around Marquana Bay, where they were surrounded by troops from the New Zealand 14th Brigade.
Split into simpler sentences: The barge depot around Horaniu was captured by US forces, and by early October 1943, only 600 Japanese soldiers remained. The garrison was hemmed into a small pocket around Marquana Bay, where they were surrounded by troops from the New Zealand 14th Brigade.