The document provides background information on Puerto Rico becoming a possession of the United States after the Spanish-American War of 1898. It discusses key figures in Puerto Rico during this transition period, including General Nelson A. Miles who led U.S. troops to take control of the island, Governor Manuel Macías y Casado who declared martial law to resist the American forces and remain loyal to Spain, and Dr. Pedro Albizu Campos who became the leader of the Puerto Rican independence movement. It also mentions William T. Sampson who commanded the blockade of San Juan harbor during the war.