Fasnacht received the country's highest award for bravery during combat, the Medal of Honor, for his action during the Battle of Spotsylvania Court House in Virginia on 12 May 1864.

After the start of the Civil War, Fasnacht enlisted in the 99th Pennsylvania Infantry.

After performing the act of gallantry earned him the Medal of Honor on 12 May 1864 during the Battle of Spotsylvania Court House, he was captured by the Confederates, after being wounded on the battlefield.

Having hid the captured flag under his shirt, he was later rescued by Union troops while being transferred to Richmond, Virginia.

The President of the United States of America, in the name of Congress, takes pleasure in presenting the Medal of Honor to Sergeant Charles H. Fasnacht, United States Army, for extraordinary heroism on 12 May 1864, while serving with Company A, 99th Pennsylvania Infantry, in action at Spotsylvania, Virginia, for capture of flag of 2d Louisiana Tigers (Confederate States of America) in a hand-to-hand contest.