When the United States demanded the withdrawal of Spain from Cuba, it was with the declaration that "The United States hereby disclaims any disposition or intention to exercise sovereignty, jurisdiction, or control over said island except for the pacification thereof, and asserts its determination, when that is accomplished, to leave the government and control of the island to its people." Never has a pledge made by a nation under such circumstances been more faithfully carried out. The administration of Cuba during the period of American military occupation was a model of its kind. General Leonard Wood, the military governor, and his associates found the cities and towns crowded with refugees and reconcentrados, and governmental affairs in a state of the utmost confusion. They established order, relieved distress, organized hospitals and charitable institutions, undertook extensive public works, reorganized the system of public schools, and put Havana, Santiago, and other cities in a sanitary condition. In a hospital near Havana Major Walter Reed, a surgeon in the United States army, demonstrated the fact that yellow fever is transmitted by the bite of a mosquito. This discovery was at once put to the test in Havana, and the city was rendered free from yellow fever for the first time in one hundred and forty years.[134] In the organization of a government for the island, the first step was to take a census of the inhabitants, determine the proper basis of suffrage, and hold municipal elections for the purpose of organizing local government. This work having been successfully accomplished, a constitutional convention, summoned by General Wood, convened in the city of Havana, November 5, 1900. By February 21, 1901, the convention had agreed upon a constitution modelled in general after that of the United States. The new constitution provided for the recognition of the public debts contracted by the insurgent government, but was silent on the subject of future relations with the United States. This subject had been brought to the attention of the convention early in February by General Wood, who had submitted for incorporation in the constitution certain provisions which had been drafted in Washington. The convention objected to these proposals on the ground that they impaired the independence and sovereignty of the island, and that it was their duty to make Cuba "independent of every other nation, the great and noble American nation included." The United States, however, had no intention of withdrawing from the island until this matter was satisfactorily adjusted. A provision, known as the Platt Amendment, was therefore inserted in the army appropriation bill of March 2, 1901, directing the President to leave the control of the island to its people so soon as a government should be established under a constitution which defined the future relations with the United States substantially as follows: