While the first shots of the Civil War were fired on Fort Sumter in Charleston Harbor in South Carolina, the first blood spilled in fighting occurred in Baltimore on April 19, 1861, when a mob of Southern sympathizers clashed with Massachusetts soldiers who'd debarked from a train on their way to Washington. Eight rioters, one bystander and three soldiers were killed, while dozens were wounded.

Situated as it was on the border between North and South, Maryland is home to Civil War sites large and small, from the sweeping landscape of the Antietam Battlefield National Park in Sharpsburg, where 23,000 men were killed, wounded or went missing in the bloodiest single day in US history, to the Surratt House Museum in the outskirts of Washington, where the conspiracy to assassinate Abraham Lincoln and other top government officials was hatched.

Here is a listing of key Civil War sites in the state:

Antietam National Battlefield, Sharpsburg, 301-432-5124, nps.gov/antm. The battle fought here in September 1862 ended the Confederate Army of Northern Virginia's first invasion of the North and led Lincoln to issue the Emancipation Proclamation freeing slaves held in areas under Confederate control.

Fort McHenry, 2400 E. Fort Ave., Baltimore, 410-962-4290, nps.gov/fomc. The harbor fort that repelled a British fleet in the War of 1812 also served as a prison camp for Southern sympathizers and Confederate prisoners of war. Exhibits and April events.

Maryland Historical Society, 20 West Monument St., Baltimore, 410-685-3750. The society's museum opens the state's largest and most comprehensive exhibit on the Civil War on April 16: interactive displays, storytellers in period costume and a "time tunnel" to transport visitors back to 1861.

Samuel Mudd House, Waldorf, 301-274-9358. The house where Lincoln's assassin, John Wilkes Booth, was treated for a broken leg as he fled Washington. Dr. Mudd was imprisoned but later pardoned.

Monocacy National Battlefield, 4801 Urbana Pike, Frederick, 301-662-3515, nps.gov/mono. Union troops under Gen. Lew Wallace confronted and delayed a Confederate army led by Gen. Jubal Early as it marched on Washington in 1864.

National Museum of Civil War Medicine, Frederick, 301-695-1864, civilwarmed.org. Exhibits devoted to treatment of sick and wounded in the war. Main museum at 48 E. Patrick St. in Frederick, but also field hospital at Antietam battlefield and house used by Clara Barton in Washington.

Point Lookout State Park, 11175 Point Lookout Road, Chesapeake Beach, Scotland, 301-872-5688. Peninsula where Potomac River meets Chesapeake Bay, used as prisoner-of-war camp for captured Confederate soldiers. Museum and nature center opens in May, with living history events planned in May, June, July and August. 11175 Point Lookout Road

South Mountain State Battlefield, Middletown, 301-791-4767, friendsofsouthmountain.org. A trio of sites in Maryland state parks on the ridge where Union and Confederate soldiers clashed before the climactic battle at Antietam in September 1862. Main site is in Gathland State Park. Events and self-guided driving tour.

Surratt House Museum, Clinton, surratt.org. Former inn where John Wilkes Booth and other Southern sympathizers met to discuss assassinating President Lincoln and key members of his government.