Thomas Jefferson advocated the acquiring of Cuba and its annexation as a state, chiefly for fear that it would be acquired by England. Later, pro-slavery leaders wanted to take the island in order to extend slave territory, as had been done in the case of Florida and Texas. Cuba's annexation was a part of the "manifest destiny" program which was rampant in the years preceding the Civil War. Many filibustering expeditions were sent there with annexation in view. The Cubans themselves often came to the United States, became naturalized citizens of this country, and would return to Cuba with an unfriendly attitude toward Spanish authority, counting for protection on their American citizenship, in case of trouble. There had often been spasmodic rebellions or outbreaks in Cuba before 1895. In 1868, there broke out what is known as the "Ten Years' War" which lasted until 1878, but the causes of these conflicts were never clearly understood by the participants on either side. Sugar cane was the principal source of Cuban wealth. According to the customary policy of trade barriers, Spain imposed duties on goods coming from the United States and the United States imposed high duties on Cuban sugar. These duties severely hurt Cuban economic life, and as economic depressions as well as prosperities are always attributed to the party in power regardless of the real causes, the Cubans, no exceptions to this rule, blamed the political power then in authority. During this "Ten Years' War" many filibustering expeditions were secretly fitted out in the United States by and for the Cubans. In 1873, a ship, the _Virginius_, sailing under American colors, carrying men and supplies to the Cuban insurgents Was captured by a Spanish gunboat. The crew and passengers were given a trial which resulted in the execution of fifty-three, of whom eight claimed to be American citizens. Immediately, the war cry Went up in the United States. But, due to the wise policy of President Grant, it never gained headway. Finally, in 1878, Spain agreed to forget the past, abolish slavery in Cuba, and admit delegates from Cuba to the Spanish Cortes or Parliament. The Cubans agreed, and hostilities ceased. All men in Cuba were given the ballot if they paid taxes to the amount of $25.00 annually, which still excluded the poorer classes. Of the representatives sent by the island to the Spanish Cortes or Parliament in Madrid, about one-fifth were Cuban born. This arrangement lasted as long as the economic life of Cuba was normal.