Helgoland Bight, Battle of, naval engagement of World War I, fought between British and German fleets on August 28, 1914. Confined to Helgoland Bight (Helgoland Bay), an arm of the North Sea to the east and south of the island of Helgoland, the action began as a raiding operation by British submarines and destroyers, supported by a flotilla of light cruisers, against German patrol vessels. The fighting during the initial phase of the battle was attended by considerable confusion, mainly because of low-lying fog. After suffering several early reverses, including the loss of a destroyer, the Germans concentrated six light cruisers in the battle area. By 11:00 a.m. the German cruiser force had secured tactical superiority over the British raiders. The British, at this juncture, directed an appeal for help to Rear Admiral David Beatty, commander of four heavy battle cruisers in reserve positions about 80 km (50 mi) north-west of Helgoland. Although the British succeeded in destroying the German cruiser Mainz before the arrival of Beatty, the Germans retained their tactical advantage, threatening the isolated British force with annihilation. The detachment commanded by Beatty reached the battle area at 12:30 p.m., and two German cruisers, the Köln and the Ariadne, were sunk in quick succession. The remainder of the German force managed to escape. Besides the destruction of four vessels, German losses included serious damage to other fleet units and more than 1,200 casualties. Through their victory, accomplished at the cost of damage to four vessels and 75 casualties, the British substantially advanced the Allied naval strategy of blockading the German coast.