The last Spanish troops in Puerto Rico sail back to Spain and the US flag is raised in most public buildings on the island formalizing U.S. control of the former Spanish colony. A military government was established under the command of General John R. Brooke.
On August 12, Spain and the United States had agreed to an armistice; on September 13, the Protocol of Peace was ratified; and on December 10, 1898, the Treaty of Paris was signed, ending the Spanish-American War. and giving the United States full control over all former Spanish military installations as well as some 120,000 acres of land formerly owned by the Spanish Crown on the island. Puerto Rico remained under direct control of US military forces until the US Congress ratified the Foraker Law on April 12th, 1900, bringing a civilian government to the island. More Spanish - American War Historical Timeline
