The Ketchum Hand Grenade,
Invented by William F. Ketchum in 1861, the Ketchum grenade, along with the grenade, was one of the most commonly used grenade design by the Union Army during the American Civil War. The Ketchum grenade featured a cast iron bomb filled with black powder, and a pressure plate which when touched off would push a firing pin against a primer, thus igniting the main powder charge. Attached to the bomb was a cardboard stabilization tail fin which guaranteed that the grenade would always land on the pressure plate, which increased the chances that it would discharge. They came in 1, 3, and 5 lb variants. The Confederates made a crude copy called the Raines Grenade, which was much less effective.
Grenades were not commonly used in the open battlefield, but saw practical use in siege battles such as Vicksburg and Petersburg. However, the detonation of the Ketchum grenade was sketchy. It was not uncommon for dozens of grenades to be thrown with only a handful detonating. After the Battle of Port Hudson, over 100 undetonated Ketchum grenades were recovered. At other battles, the Confederates would learn to cover their defensive works with blankets so that the grenades would land harmlessly and be thrown back at Union troops.