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, took place August 8 – August 9, 1942. It was a naval battle of the Pacific Campaign of World War II, between the Imperial Japanese Navy and Allied naval forces.

In the battle, a Japanese warship task force surprised and routed the Allied naval force, sinking one Australian and three American cruisers, while taking only moderate damage in return. The Japanese force consisted of seven cruisers and one destroyer, commanded by Vice Admiral Gunichi Mikawa. Five cruisers and seven destroyers were involved in the battle.

As a result of the defeat, the remaining Allied warships and the amphibious force withdrew from the Solomon Islands. This temporarily conceded control of the seas around Guadalcanal to the Japanese. Allied ground forces had landed on Guadalcanal and nearby islands only the day before. The withdrawal of the fleet left them in a precarious situation.