SHARPSBURG, Md. (AP) – Two Civil War battlefields in Maryland are ringing bells to mark the 150th anniversary of Confederate Gen. Robert E. Lee’s surrender.

The Antietam National Battlefield near Sharpsburg and the Monocacy (mah-NAH’-kah-see) National Battlefield near Frederick are ringing bells for four minutes Thursday starting at 3:15 p.m. The four minutes symbolize the four years of the war.

The National Park Service is asking churches and local governments to join in.

Lee commanded the Army of Northern Virginia. He surrendered to Union Lt. Gen. Ulysses Grant at Appamattox, Virginia, on April 9, 1865.