Developed and designed as a protection defense line envisioned for Charleston Harbor (after The War of 1812), Ft. Sumter's construction began in 1829. The Fort is of a Quadrangular structure, comprised of 70,000 tons of New England granite – built onto a reinforced natural sandbar (about 34-acres) and located roughly 1-mile outside of Charleston Harbor. Still not complete in 1861, the Fort was designed to garrison some 650 Officers and men and featured 3-tiered artillery emplacements in each of it's walls (holding around 135 guns total). Reinforced by brick, the Fort's walls are 5 feet thick and roughly 170 to 190 feet high. Fort Sumter is important in American history as being the site of the start of The Civil War (1861-65). Garrisoned by a small detachment of Union soldiers when South Carolina (US), left The Union to form The Confederacy – Confederate forces on the landward side of Charleston Harbor (bristling with artillery batteries), threatened action if the Fort was resupplied or failed to surrender. On April 12, 1861 – Rebel Forces opened fire on Fort Sumter in a spectacular 34-hour continuous bombardment. Faced with no re-supply and running low on ammunition – the Fort's Commander agreed to surrender. The garrison was allowed to leave the fort “with honor”. Fort Sumter would become the focus of continued and unrelenting artillery attacks from the Union Naval Blockade. By the end of The War in 1865, Fort Sumter resembled a pile of rocks (with very little structures left standing). The US Army rebuilt the Fort and re-stocked some of her cannon (now for Coastal Defense use). The third Upper gun level was not rebuilt. From 1876 to 1897, Fort Sumter was used as a Lighthouse for Charleston Harbor. During The Spanish American War, the Fort was reconditioned and re-garrisoned. Fort Sumter was used during World War I and II for observation against possible German U-Boat attacks. In 1966, Fort Sumter became a National Monument. It can be visited today.