Historic Marker number 70 is in Fort Zachary Taylor State Park located at the end of Southard Street in Truman Annex.Fort Zachary Taylor was built in 1845. At the time, it was located 1,200 feet from the shores of Key West. The fort stood three stories tall, held 140 cannons, and was home to 450 soldiers."Fort Zach," as locals call it, was part of the Third Tier System of Defense, which called for the construction of masonry fortresses to prevent sea attacks on the United States. The need for these defenses was a direct outcome of the War of 1812 in which the British burned the U.S. Capital to the ground during a sea-based invasion. Fort Taylor and Fort Jefferson in the Dry Tortugas were important defensive structures for the United States. Together, they held command over the waters of the Straits of Florida and the Gulf of Mexico.During the Civil War, Fort Taylor remained under Union control and played a crucial role in the sea blockade that is credited with shortening the war and averting the deaths of untold numbers of soldiers on both the Union and Confederate sides of the conflict.The current form of the fort is largely due to ever changing military needs. In 1889, with the advent of rifled artillery, most masonry fort structures were deemed obsolete. In preparation for the Spanish American War, Fort Taylor was transformed into a single story structure. The upper two floors of the fort were removed and the materials were used to fill in the casements.A further example of the change in military needs can be seen in one of the 3 Civil War era forts on the island. At the same time Fort Taylor was being updated, a partial demolition of West Martello Fort took place. While there are many myths about the destruction of the fort, it is believed that much of the brickwork was removed to fill the casements and fortify the outer walls of Fort Taylor. (See Historic Marker 54.)By the time the Spanish American War began in 1898, the fort had been reconfigured for two new rifled artillery batteries. From a defensive perspective, the shorter stature of its defensive walls was less of an obstacle and target on the horizon.By 1947, the fort was of no use to the army and it was turned over to the U.S Navy. In 1968 volunteers excavated Civil War guns and ammunition that had been buried in long-abandoned parts of the fort. These efforts eventually unearthed the discovery of the nation's largest collection of Civil War cannons. Many of these have been refurbished and stand guard in their original gun ports.As a result of channel dredging in the mid twentieth century, the fort became land-locked. In its current use, it sits in the middle of 87 acres of park land, and is now known for the best beach in Key West.Fort Taylor was placed on the National Register of Historic Places in 1971, and was designated a National Historic Landmark in 1973.The fort's looks and uses have changed drastically since its inception in 1845. Having ended its military service in 1947, it should be remembered for its service to the United States during the Civil War, Spanish-American War, World War I, and World War II.