Military History of Puerto Rico

In 1890, Captain Alfred Thayer Mahan, a member of the Navy War Board and leading U.S. strategic thinker, published a book titled The Influence of Sea Power upon History in which he argued for the establishment of a large and powerful navy modeled after the British Royal Navy. Part of his strategy called for the acquisition of colonies in the Caribbean, which would serve as coaling and naval stations. They would serve as strategic points of defense with the construction of a canal through the Isthmus of Panama, to allow easier passage of ships between the Atlantic and Pacific oceans.

William H. Seward, the former Secretary of State under presidents Abraham Lincoln and Andrew Johnson, had also stressed the importance of building a canal in Honduras, Nicaragua, or Panama. He suggested that the United States annex the Dominican Republic and purchase Puerto Rico and Cuba. The U.S. Senate did not approve his annexation proposal, and Spain rejected the U.S. offer of 160 million dollars for Puerto Rico (area: 9,104 sq. km) and Cuba (area: 109,884 sq. km).  Unfortunately, this was a situation which the Spanish officials later came to regret.

Since 1894, the United States Naval War College had been developing contingency plans for a war with Spain. By 1896, the U.S. Office of Naval Intelligence had prepared a plan that included military operations in Puerto Rican waters. Except for one 1895 plan, which recommended annexation of the island then named Isle of Pines (later renamed as Isla de la Juventud), a recommendation dropped in later planning, plans developed for attacks on Spanish territories were intended as support operations against Spain's forces in and around Cuba.