Hardtack

Hardtack is a simple type of dense biscuit or cracker made from flour, water, and sometimes salt. Hardtack is inexpensive and long-lasting. It is used for sustenance in the absence of perishable foods, commonly during long sea voyages, land migrations, and military campaigns. Along with salt pork, hardtack was a standard ration for many militaries and navies from the 17th through the early 20th centuries.