World War II: Battle of Savo Island: Allied naval forces protecting their amphibious forces during the initial stages of the Battle of Guadalcanal are surprised and defeated by an Imperial Japanese Navy cruiser force.

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 Battle of Savo Island, also known as the First Battle of Savo Island and in Japanese sources as the First Battle of the Solomon Sea , and colloquially among Allied Guadalcanal veterans as the Battle of the Five Sitting Ducks, was a naval battle during the Solomon Islands campaign of the Pacific War of World War II between the Imperial Japanese Navy and Allied naval forces. The battle took place on 8–9 August 1942 and was the first major naval engagement of the Guadalcanal campaign, the first of several naval battles in the straits later named Ironbottom Sound, near the island of Guadalcanal.

The Allies, formally referred to as the United Nations from 1942, were an international military coalition formed during World War II (1939–1945) to oppose the Axis powers. Its principal members were the "Big Four" – the United Kingdom, United States, Soviet Union, and China.

The Guadalcanal campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by the United States, was an Allied offensive against forces of the Empire of Japan in the Solomon Islands during the Pacific Theater of World War II. It was fought between 7 August 1942 and 9 February 1943, and involved major land and naval battles on and surrounding the island of Guadalcanal. It was the first major Allied land offensive against Japan during the war.