1941, 3 (2) in 1942, none in 1943 and 1 (0) in 1944. Most were scheduled operations and 3 were emergency cases. The ports used were Vigo (7–8), Las Palmas (6), Cádiz (6) and El Ferrol (5). Overall, there were 1,508 tons of gas, oil and 37.1 tons of heavy oil pumped; in most cases there was also lubricants, water and food delivered, in some cases navigation charts and first-aid kits. Also 3 cases that were delivered are torpedoes. In a few cases injured or sick German sailors were taken off the ship. Almost all cases were overnight operations, though two emergency repairs took a few days. There were four German supply ships (Thalia, Bessel, Max Albrecht and Corrientes) involved. In one case the replenishment operation was abandoned, as it turned out that the submarine in question was damaged and unfit for the process. The Corrientes was the target of a limpet mine attack while at port in Las Palmas on 9 May 1940, but the damage was minor and she was back in service a few weeks later. Occupation of Tangier Spanish troops occupied the Tangier International Zone on 14 June 1940, the same day Paris fell to the Germans. Despite calls by the writer Rafael Sánchez Mazas and other Spanish nationalists to annex Tangier, the Franco regime publicly considered the occupation a temporary wartime measure. A diplomatic dispute between Britain and Spain over the latter's abolition of the city's international institutions in November 1940 led to a further guarantee of British rights and a Spanish promise not to fortify the area. In May 1944, although it had served as a contact point between him and the later Axis Powers during the Spanish Civil War, Franco expelled all German diplomats from the area. The territory was restored to its pre-war status on 11 October 1945. In July 1952 the protecting powers met at Rabat to discuss the Zone's future, agreeing to abolish it. Tangier joined with the rest of Morocco following the restoration of full sovereignty in 1956. Volunteers The main part of Spain's involvement in the war was through volunteers. They fought for both sides, largely reflecting the allegiances of the civil war. Spanish volunteers in Axis service Although Franco did not bring Spain into World War II on the side of the Axis, he permitted volunteers to join the German Army on the clear and guaranteed condition