After the initial troop deployment on Guadalcanal on 7 August, Allied naval forces rushed to move supplies ashore for the Marines currently engaging Japanese defenders. Over the next few days three perimeter patrols were set up to protect the north, south and eastern approaches to the area in which the supply ships were operating. On 8–9 August, following a series of Allied communication blunders, a force of eight warships under command of Vice-Admiral Mikawa was able to launch a devastating surprise attack under cover of darkness. Mikawa opened fire on the southern patrol before moving up to engage the northern patrol between Savo and Florida Islands. Having been caught completely off guard, the Allies lost over 1,000 men and four heavy cruisers, with the Japanese ships only suffering minor damage. The Japanese made a hasty retreat expecting US carrier attacks, unaware that they had already vacated the area.
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