Complex sentence: Intelligence gathered by Coastwatchers and landing parties had determined that there were few suitable landing beaches, with the only viable options being located in Empress Augusta Bay, around Cape Torokina on the western coast of Bougainville.
Split into simpler sentences: Intelligence gathered by Coastwatchers and landing parties had determined that there were few suitable landing beaches. The only viable options were located in Empress Augusta Bay, around Cape Torokina on the western coast of Bougainville.