World War II: American forces defeated the Japanese at the Third Battle of the Matanikau in Guadalcanal, Solomon Islands, reversing the Japanese victory a couple of weeks earlier.

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

The Actions along the Matanikau—sometimes referred to as the Second and Third Battles of the Matanikau—were two separate but related engagements between the United States and Imperial Japanese naval and ground forces in the Pacific theater of World War II. The actions occurred around the Matanikau River on Guadalcanal Island in the southwestern Pacific during the Guadalcanal campaign. These particular engagements—the first taking place between 23 and 27 September, and the second between 6 and 9 October—were two of the largest and most significant of the Matanikau actions.

Guadalcanal is the principal island in Guadalcanal Province of Solomon Islands, located in the southwestern Pacific Ocean, northeast of Australia. It is the largest island in the Solomons by area and the second-largest by population. The island is mainly covered in dense tropical rainforest and has a mountainous hinterland.

Solomon Islands, also known simply as the Solomons, is an island country consisting of six major islands and over 1,000 smaller islands in Melanesia, Oceania, to the north-east of Australia. It is directly adjacent to the Autonomous Region of Bougainville to the west, Australia to the south-west, New Caledonia and Vanuatu to the south-east, Fiji, Tuvalu, and Wallis and Futuna to the east, and the Federated States of Micronesia and Nauru to the north. It has a total area of 28,896 square kilometres, and a population of 734,887 according to the official estimates for mid-2023. Its capital and largest city, Honiara, is located on the largest island, Guadalcanal. The country takes its name from the wider area of the Solomon Islands archipelago, which is a collection of Melanesian islands that also includes the Autonomous Region of Bougainville, but excludes the Santa Cruz Islands.