During the Spanish–American War, the United States Army, United States Marine Corps, and United States Navy fought 30 significant battles against the Spanish Army and Spanish Navy. Of these, 27 occurred in the Caribbean theater and three in the Pacific theater. The Caribbean theater consisted of two campaigns — the Puerto Rico campaign, which had ten battles, and the Cuba campaign, with 17 battles — while the Pacific theater had one campaign — the Philippine campaign, with two battles — and the capture of Guam. Overview The United States Navy battleship was mysteriously sunk in Havana harbor on 15 February 1898; political pressures from the Democratic Party pushed the administration of Republican President William McKinley into a war that he had wished to avoid. Spain promised multiple times that it would reform the government of Cuba, but never delivered. The United States sent an ultimatum to Spain demanding that it surrender control of Cuba on 20 April. After the ultimatum was sent, Madrid declared war on 23 April and Washington responded with its own declaration two days later. The main issue was Cuban independence; the ten-week war was fought in both the Caribbean and the Pacific. After the declaration of war, the U.S. Navy blockaded ports such as Havana and Cardenas. The Spanish attempted to lift the blockades on Cardenas and Matanzas, finally succeeding after failing once at Cardenas. Commodore Dewey successfully destroyed the Spanish Pacific Fleet in Manila Bay on May 1, but failed to land troops. The Navy also blockaded Puerto Rico and bombarded San Juan, but the Spanish attempted to lift this blockade, succeeding on the second attempt in June. The U.S. Marines also cut telegraph lines under the bay of Cienfuegos, but suffered heavy losses from Spanish fire. The U.S. also captured the port of Guantánamo Bay after a four-day battle, which ended on June 10. U.S. expeditionary forces landed in Cuba on 22 June and skirmished successfully at Las Guasimas two days later. Meanwhile, the island of Guam was "captured" by the Americans, which consisted of raising of the American flag. The U.S. also attempted to land forces near Trinidad, but were repulsed by Spanish forces. The U.S. forces captured San Juan Heights, which overlooked Santiago de Cuba, after two battles at San Juan Hill and Kettle Hill, which was preceded by a smaller battle on the San Juan Hill's right flank at El Caney.