The battle was a daylight surface engagement in which air support played no role and in which the outnumbered American force escaped greater damage after the Japanese chose to withdraw.

On the night of 19/20 February 1943, the patrol force, consisting of the heavy cruiser Indianapolis and the destroyers Coghlan and Gillespie shelled and sank the Japanese transport ship Akagane Maru (3100 GRT) west of Attu.

[5] Because of the remote location of the battle and its being a chance encounter on the open ocean, neither fleet had air or submarine assistance, making this one of the few engagements exclusively between surface ships in the Pacific Theater and one of the last pure gunnery duels between fleets of major surface combatants in naval history.

[1] Although the Japanese cruisers heavily outgunned the American force and inflicted more damage, the engagement was tactically inconclusive.

The U.S. Navy warships escaped destruction after a Japanese misjudgment, when, with the Japanese fleet on the edge of victory, Admiral Hosogaya – not realizing the heavy damage his ships had inflicted and fearing American war planes would appear – chose to retreat, conceding a strategic victory to the US Navy.

[4][7] Indeed, the battle ended Japanese attempts to resupply the Aleutian garrisons by surface ship, leaving only submarines to conduct supply runs.

[1] Hosogaya was accordingly retired from active service after the battle and assigned to govern a group of South Pacific islands.