Hardtack was a biscuit great for soldiers
People say that hardtacks can even stop a bullet. This saying is not true, unfortunately. These hard biscuits have been around for a long time, although they have changed their appearance over the centuries. Hardback is famously known for being the food for long sea voyages, land explorations, and military campaigns.
These biscuits are basically bread that does not rise, similar to a cracker. Many militaries have hardtack in their food supplies as it is quite easy to pack into a bag and carry. During the American Civil War, the resources were scarce, so this was the main meal for the soldiers.