that engaged in intermittent warfare, as well as a small population of foreign traders and missionaries. Spanish control over the islands was nominal. The Spaniards stopped to raise a flag over Chuuk in 1886, and returned in 1895 as part of an attempt to assert control and negotiate peace between warring Chuukese tribes. No permanent Spanish settlement was ever established, and tribal violence continued until the German colonial era. The Caroline Islands were sold to the German Empire in 1899, after Spain withdrew from the Pacific in the aftermath of the Spanish–American War. During the First World War, The Japanese Navy was tasked with pursuing and destroying the German East Asiatic Squadron and protection of the shipping lanes for Allied commerce in the Pacific and Indian Oceans. During the course of this operation, the Japanese Navy seized the German possessions in the Marianas, Carolines, Marshall Islands and Palau groups by October 1914. Chuuk then became a possession of the Empire of Japan under a mandate from the League of Nations following Germany's defeat in World War I. World War II Naval Base Truk, during World War II in the Truk Lagoon was the Empire of Japan's main base in the South Pacific theatre. Truk was a heavily fortified base for Japanese operations against Allied forces in New Guinea and the Solomon Islands, serving as the forward anchorage for the Japanese Imperial Fleet. Truk Lagoon was considered the most formidable of all Japanese strongholds in the Pacific. On the various islands, the Japanese Civil Engineering Department and Naval Construction Department had built roads, trenches, bunkers and caves. Five airstrips, seaplane bases, a torpedo boat station, submarine repair shops, a communications center and a radar station were constructed during the war. Protecting these various facilities were coastal defense guns and mortar emplacements. The Japanese garrison consisted of 27,856 IJN men, under the command of Vice Admiral Masami Kobayashi, then Vice Admiral Chuichi Hara, and 16,737 IJA men, under the command of Major General Kanenobu Ishuin. Due to its heavy fortifications, both natural and manmade, the base at Truk was known to Allied forces as "the Gibraltar of the Pacific". A significant portion of the Japanese fleet was based at Truk, with its administrative center on Tonoas (south of Weno). At anchor in the lagoon, were the Imperial Japanese Navy's battleships, aircraft carriers, cruisers, destroyers, tankers, cargo ships, tugboats, gunboats, minesweepers, landing craft,