The Civil War is one of the darkest and most tragic chapters in our nation’s history. Even today, the war and its fallout still influence our culture and politics. One of the best ways to learn about the Civil War and reflect upon it is to visit battlefields where Union and Confederacy forces fought. Most are now preserved and maintained by the National Park Service as National Military Parks. Following are 12 everyone should visit.

1. Gettysburg, Pennsylvania

Fought over three days (July 1-3) in 1863, the Battle of Gettysburg claimed over 51,000 casualties, more than any other Civil War Battle. It was the turning point in the war as Union forces stopped the advance of Robert E. Lee’s army, and it was the site of Lincoln’s famous Gettysburg Address. Although the war would rage on for 2 more years, the Confederacy was almost always on its heels after Gettysburg.

2. Antietam, Maryland

In 1862, Lee made his first invasion of the North, and Antietam is where General George McClellan stopped him. It was the bloodiest single-day battle of the war, with more than 23,000 casualties.

3. Vicksburg, Mississippi

The Battle of Vicksburg, fought from May to July 1863, was another major turning point in the war. By winning the battle, the Union took control of the Mississippi River, dealing a blow to the Confederacy’s supply chains.

4. Chickamauga, Tennessee

The Battles of Chickamauga and Chattanooga are both preserved in the same park. At Chickamauga, which took place over 2 days in September 1863, the casualties amounted to the second-most of any battle in the war.

5. Chattanooga, Tennessee

After the victory at Chickamauga, the Union set its sights next on Chattanooga, an important city during the war. Generals Grant and Sherman laid siege to the city, and their eventual victory paved the way for Sherman’s march to Atlanta.

6. Petersburg, Virginia

During the 1864-65 siege of this city not far south of Richmond, capital of the Confederacy, Grant fatally crippled Lee’s forces. After that, the end was just a matter of time.

7. Bull Run/Manassas, Virginia

Manassas National Battlefield Park commemorates the First Battle and Second Battle of Bull Run. The first one was in 1861 and was the first major conflict of the war, with the Confederates winning. The Confederacy won the second one as well, in 1862. Nearly 20,000 people died there over 3 days of battle.

8. Shiloh, Tennessee

In 1862, Union troops on the Tennessee River landed here, and the surprise attack they sustained was one of the first major battles in the Western theater. Ultimately, Grant prevailed in this bloody battle that saw over 23,000 casualties in 2 days.

9. Fredericksburg, Virginia

Fredericksburg and Spotsylvania National Military Park preserves the sites of 4 battles, which include this one and the next two on this list. Fought over 4 days in December 1862, the Battle of Fredericksburg was a Confederate victory that claimed about 17,000 lives.

10. Chancellorsville, Virginia

The Battle of Chancellorsville was another 4-day struggle, this time in May 1863, that the Confederates won. However, it’s probably best known as the place where famed Confederate General “Stonewall” Jackson died, accidentally shot by his own men. Jackson didn’t die during the battle itself; he died 8 days later from pneumonia and other complications stemming from his wounds.

11. Wilderness, Virginia

The battle here lasted for 3 days in May 1864. Although the battle itself was inconclusive, it’s notable for, aside from its heavy casualty counts, as the beginning of Grant’s Overland Campaign, a period of combat and maneuvers that lasted around 40 days and spanned the area between the Rapidan and James Rivers.

12. Harper’s Ferry, West Virginia

One of the most famous Civil War towns, Harper’s Ferry had strategic importance by virtue of sitting at the confluence of the Shenandoah and Potomac Rivers. Control of the town changed hands 14 times during the war. Harper’s Ferry is also famous for being the place where abolitionist John Brown staged a raid during the pre-war years in hopes of starting a slave rebellion.