The campaign also influenced US Marine Corps amphibious operations during the Pacific War, and continues to influence US amphibious doctrine. During the interwar period the campaign "became a focal point for the study of amphibious warfare" in the United Kingdom and United States, because it involved the four types of amphibious operations: the raid, demonstration, assault and withdrawal. Analysis of the campaign before World War II led to a belief among many armed forces that amphibious assaults could not succeed against modern defences. The perception continued until the Normandy Landings in June 1944, despite some successful examples of amphibious operations earlier in the war, such as those in Italy, and at Tarawa and in the Gilbert Islands in the Pacific. Although the negative perception prevailed among Allied planners in the interwar years, the war situation after 1940 meant that such operations had to be considered. However, despite early successes in North Africa and Italy, it was not until Normandy that the belief that opposed landings could not succeed was completely excised. Interwar developments One of the first amphibious landings involving armour was conducted by the Irish National Army in 1922, during the Irish Civil War. Landings against Republican rebels at Westport, Fenit and Cork all involved armour cars. The Westport and Fenit landings involved light armoured cars and 18-pounder artillery guns being hoisted off the ships by crane. Heavier armoured cars were used at Cork, resulting in some difficulty. While Irish troops could reach the coast in small boats from naval vessels offshore, the ships had to dock to unload the heavy vehicles and artillery guns. These operations were a major success for the Irish government forces, mainly due to the element of surprise and the use of armoured vehicles and artillery. Government forces were able to capture all the major towns and cities in southern Ireland. The Alhucemas landing on 8 September 1925, performed by a Spanish-French coalition against rebel Berber tribesmen in the north of Morocco, was an amphibious landing where tanks were used for the first time and massive aerial and naval gunfire support was employed by the landing forces, directed by spotting personnel with communication devices. Floating depots were organized with medical, water, ammunition and food supplies, to be dispatched ashore when needed. The barges used in this landing were the surviving "K" boats from Gallipoli, upgraded in Spanish shipyards. In 1938, Japanese forces attacked Chinese