After the Battle of Midway the time was right to begin a campaign to begin to retake the Pacific. The Allies decided that the first step would be the Solomon Islands that stood astride the sea lanes to Australia. They decided on Guadalcanal, Tulalgi and Florida Island as a start. The Japanese had gained control of Tulagi in May and built a seaplane base there. In July the allies discovered that the Japanese were building an airfield on Guadalcanal. That airfield they feared would accommodate long range aircraft that could attack Allied sea lanes. This spurred the Allies to advance their plans.

Vice Admiral Robert Ghormley took command of of the Southern Pacific theater on June 19, 1942. The 1st Marine Division commanded General Alexander Vandefrift was tasked with capturing the islands. The Allies prepared their force of 75 warships and transports called Watchtower.

The task force arrived off the islands on the night of August 6th. Thanks to bad weather the task force arrived undetected. 3,000 Marines assaulted Tulagi and nearby Gavutu and Tanambogo, the Japanese fought to the last man, but with two days both islands were secured at the cost of 122 Marine lives.

At 9:10 Am on August 7th 11,000 US Marines came ashore. They met very little resistance and by the next day had secured their first objective the airfield. The Japanese had abandoned the field. In the meantime Japanese land based aircraft attacked the ships participating in the landing sinking one and damaging another. The Japanese let 36 aircraft but the US lost 19. Admiral Fletcher fearing that he would not have enough aircraft available to defend his ships in harbor ordered the carriers to depart in the evening of April 8th and the transports the next day, even though they had only unloaded half their supplies. That night the Japanese attacked.

The Japanese led by Admiral Mikawa sent a task force of five heavy cruisers, two light cruisers and a destroyer to attack the American forces off the island. To guard the transport the allies had five heavy cruisers and a destroyer. The American group was divided into two groups and totally unaware of the approach of the Japanese ships. The battle began when Japanese float planes flying unmolested above the American cruisers released flares. Within moments Japanese guns had set the HMAS Canberra on fire. Moments later USS Chicago was similarly enveloped. Soon the Japanese turned their attention to the Northern group and the Astoria, Quincy and Vincensses were soon out of action and ablaze. Thus in the worse defeat in surface warfare in its history the US navy together with the Australians lost five cruisers without inflicting significant casualties on the enemy.