While the Cuban convention was deliberating, it became apparent that the constitution would not include any statement of a policy in regard to future relations with the United States. The American Senate, therefore, under the leadership of Senator O.H. Platt, passed the so-called "Platt Amendment." Its several provisions were as follows: the Cuban government shall never enter into agreements with other powers which tend to impair the independence of the island; it shall not contract public debts of such size that the ordinary revenues would be inadequate to pay interest charges and provide for a sinking fund; it shall permit the intervention of the United States when needed to preserve Cuban independence and the maintenance of an adequate government; and it shall sell or lease necessary coaling stations to the United States. When satisfied that the purpose of the Amendment was not to enable the United States to meddle in affairs in Cuba, but merely to secure Cuban independence and set forth a definite understanding between the two nations, the convention incorporated it in the final constitution. On May 20, 1902, the control of Cuba was formally relinquished to the people of the island, with the good wishes of the people of the United States. Only once since that time has the United States intervened. During the summer of 1906, an insurrection against the Cuban government took place during which the president of the Republic requested American assistance. A small army was despatched, which remained until March, 1909, when quiet was restored and an orderly election was held. The task of the United States in Porto Rico was far simpler than in Cuba. The island was small; the people homogeneous, predominantly white, and well-disposed toward American occupation; and only slight damage had been done by the troops during the war because of the cessation of hostilities at the outset of the Porto Rican expedition. The development of a system of education, therefore, the improvement of roads and the betterment of health conditions through vaccination and the control of yellow fever presented a problem which was relatively simple.