The land and naval battles at Santiago brought the Spanish War to an end. For several weeks the army kept up the investment, with health and morale steadily deteriorating. On July 17 the Spanish army at Santiago was surrendered. On July 27 an invasion of Porto Rico under General Miles took place, and on August 12 the preliminaries of peace were signed on behalf of Spain by the French Minister at Washington. Manila fell the next day, and the war closed with the American army in possession of the most valuable of Spain's remaining colonies. The Spanish and American peace commissioners met in Paris in October to fix a basis for settlement. An American demand that Cuba should be set free, without debt, and left to the tutelage of the United States, and that Porto Rico should become an American possession, was formulated early in the autumn. There was less certainty about the retention of the Philippines, for here the desire for expansion was checked by a conservative opposition to the adoption of foreign colonies. The evil effects of imperialism were already being pictured by those who had opposed the war. The difficulties of returning the islands to Spain were greater than those involved in their retention, and McKinley finally determined that the cession must include the Philippine Archipelago, and the island of Guam in the Ladrones. The chief of the American commissioners was William R. Day, who had become Secretary of State early in the war, and who was succeeded in that post by John Hay. Under his direction the Treaty of Paris was signed December 10, 1898. The war and the conquest of the Philippines hastened another though peaceful expansion. The Hawaiian Islands had been a matter of interest to the United States since the American missionaries had begun to work there in the thirties. A growing, American, sugar-raising population had long hoped for annexation and had carried out a successful revolution shortly before 1893. Harrison had concluded a treaty of annexation with the provisional government, but Cleveland had refused to approve it. On July 7, 1898, however, the Newlands Resolution accomplished the annexation of the republic, and in 1900 a regular territorial government was provided for the group of islands. The spectacular journey of the Oregon around Cape Horn revived the demand for an isthmian canal. Expansion suddenly took possession of the American mind, and a new idea of duty, summed up by Rudyard Kipling in _The White Man's Burden_, filled a large portion of the press.