An engraving depicts Union troops charging across the Burnside bridge over Antietam Creek during the Battle of Antietam near Sharpsburg, Md., on Sept. 17, 1862. (AP)

The Battle of Antietam, with the highest casualty rate of any single-day battle in the Civil War, will be commemorated this weekend by the National Park Service, the town of Sharpsburg, a battle reenactment group and organizers of a first-time walk from Sharpsburg, Md., to Shepherdstown, W.Va.

Although Monday, Sept. 17, is the 150th anniversary of the battle — also known as the Battle of Sharpsburg — activities will be spread over four days, beginning Sept. 14.

The National Park Service has the most extensive program, with dozens of daily events that will begin Friday and run through Monday. Those will include guided tours of the battlefield, various memorials and historic sites, as well as weapon demonstrations and concerts by period bands. Also scheduled are talks by some of the best Civil War authors in the country, including Drew Gilpin Faust, James “Bud” Robertson, Mark Neely and James McPherson.

Another star of the Civil War community, Ed Bears, will also participate. He is considered the dean of battlefield tour guides and is well-known for his phenomenal memory as well as his fast-paced hikes. Even at 89, he can wear out much younger participants. On Saturday at 1 p.m., join him for a 90-minute hike through the North Woods.

All events at the park are open to the public and no reservations are needed. The only cost is the standard park entrance fee of $4 per adult or $6 for a family.

On Saturday and Sunday, the town of Sharpsburg holds its annul Heritage Festival , with food, music, crafts and art. Civil War reenactors will be on hand to discuss the war, and a ghost tour is promised. There is no entrance fee.

If it’s a battle reenactment you want to see, there will be two each on Sept. 15 and 16 at Legacy Manor Farm, two miles north of Sharpsburg. The three-day event opens Friday with visits to Union and Confederate generals as they sit in their headquarter tents discussing strategies for the upcoming battle.

Author Jeff Shara is scheduled to discuss his newest book at 1 p.m. Saturday, and that evening, a remembrance illumination will be held at 7 p.m.

The cost of a one-day ticket for youths under age 12 is $9, and an adult one-day ticket is $19.

On Sunday, a first-time “Antietam Remembrance Walk” is scheduled from Sharpsburg, crossing over the Potomac River, to Shepherdstown, W.Va. It will honor the men who fought at Antietam and the residents of both towns who opened their doors to the wounded.

There is no charge to participate in the three-mile walk, which begins at the Antietam Railroad Station at 5:30 p.m., but registration is encouraged. Shuttle buses will be available to return visitors to Sharpsburg.

For more, see our Civil War 150 special section.