Key West outpost during the Civil War. Construction began in 1861 on two other forts, East and West Martello Towers, which served as side armories and batteries for the larger fort. When completed, they were connected to Fort Taylor by railroad tracks for movement of munitions. Early in 1864, 900 men from the 2nd United States Colored Troops (USCT) arrived in Key West as replacements for the 47th Pennsylvania Volunteers. Many of these men would see action in southern Florida and the 2nd USCT would become "one of the most active" black regiments in Florida. Fort Jefferson, located about from Key West on Garden Key in the Dry Tortugas, served after the Civil War as the prison for Dr. Samuel A. Mudd, convicted of conspiracy for setting the broken leg of John Wilkes Booth, the assassin of President Abraham Lincoln. In the 19th century, major industries included wrecking, fishing, turtling, and salt manufacturing. From 1830 to 1861, Key West was a major center of U.S. salt production, harvesting the commodity from the sea (via receding tidal pools) rather than from salt mines. After the outbreak of the Civil War, Union troops shut down the salt industry after Confederate sympathizers smuggled the product into the South. Salt production resumed at the end of the war, but the industry was destroyed by an 1876 hurricane and never recovered, in part because of new salt mines on the mainland. During the Ten Years' War (an unsuccessful Cuban war for independence in the 1860s and 1870s), many Cubans sought refuge in Key West. Several cigar factories relocated to the city from Cuba, and Key West quickly became a major producer of cigars. A fire on April 1, 1886, that started at a coffee shop next to the San Carlos Institute and spread out of control, destroyed 18 cigar factories and 614 houses and government warehouses. Some factory owners chose not to rebuild and instead moved their operations to the new community of Ybor City in Tampa, leading to a slow decline in the cigar industry in Key West. Still, Key West remained the largest and wealthiest city in Florida at the end of the 1880s. sailed from Key West on her fateful visit to Havana, where she blew up and sank in Havana Harbor, igniting the Spanish–American War. Crewmen from the ship are buried in Key West, and the Navy investigation into the blast