Cap boxes don’t get much respect. The little black pouches hung off soldiers’ belts, often overshadowed by their martial neighbors, eye-catching brass belt buckles and scabbards that held wicked-looking bayonets. Veterans wrote poems in praise of their canteens, a cartridge box became the centerpiece of the badge for the Union’s 15th Corps. But no odes, and little acclaim, recorded for the cap box.

Yet they were among the most important pieces of gear in a soldier’s kit. Cap boxes carried their namesake, percussion caps, the revolutionary little copper top hats that served as the priming system for muskets, many cavalry carbines, and even some breechloading rifles. To discharge his weapon, a soldier placed a percussion cap on the cone, or nipple, of his firearm. When the trigger was pulled, the hammer flew forward and forcefully struck the percussion cap. The impact ignited an explosive fulminate of mercury compound inside the cap, creating a spark that dropped through the cone and ignited the powder charge in the barrel, sending a lethal lead missile downrange.

The percussion system was invented in the 1820s, and two decades later it became the standard for the U.S. Army with the issue of the Model 1842 musket. 

Troops then needed a way to carry the small percussion caps. Initially, small pockets were cut into issue jackets to hold the caps, but they did not prove satisfactory. By about 1845, U.S. troops were issued the first cap boxes. During the Civil War thousands upon thousands were stitched up for Union and Confederate troops. 

  • An inner flap, complete with little “ears” sewn on the side, helped hold in the caps and provided additional protection from moisture. (Dana B. Shoaf Collection/Photos by Melissa A. Winn)
  • (Dana B. Shoaf Collection/Photos by Melissa A. Winn)
  • Cap boxes had loops on the back to attach the accoutrement to a belt. If you look closely at the soldier image, left, you can see the top of the loops just above the body of the box. Rivets were sometimes applied, as here, to reinforce the hand stitching. Some Confederate-made cap boxes had one wide belt loop on the back to speed production. (Dana B. Shoaf Collection/Photos by Melissa A. Winn)
  • Above, a strip of sheep’s wool was sewn into the box to prevent percussion caps from falling out. Next to the wool, but out of sight here, was a narrow leather channel that held a metal “cone pick.” Left, many Union Army cap boxes incorporated a leather tab integral to the front flap that buttoned over a brass finial. (Dana B. Shoaf Collection/Photos by Melissa A. Winn)
  • Small, critical copper percussion caps could easily be lost, and the cap box kept the vital primers close at hand. (Dana B. Shoaf Collection/Photo by Melissa A. Winn)
  • Every bundle of 10 cartridges included a paper tube, like the original, above, with 12 percussion caps a soldier would dump into his cap box. In the Allegheny Arsenal diagram on P. 49, the “percussion cap room” is where the youngest female arsenal workers placed percussion caps in tubes. (Heritage Auctions, Dallas)
  • A Confederate soldier wearing a Louisiana state belt buckle brandishes his smoothbore musket, a flintlock converted to percussion.
    A Confederate soldier wearing a Louisiana state belt buckle brandishes his smoothbore musket, a flintlock converted to percussion. His cap box is a prewar design called a “shield front” because of the shape, and the closing tab is a separate piece of leather sewn on the flap. Union troops also used this style of cap box. (Library of Congress)
  • The Confederate-made cap box might not win a fashion show, but it did its job. (Don Troiani/Bridgeman Image)
  • The cap “pouch” was imported from England and used by Confederates and a few Union regiments. The pouch was made to be worn on the cartridge box sling, which slid through the angled attachment loop. (Don Troiani/Bridgeman Image)