Ship's biscuit

Hardtack

A preserved hardtack at a museum display
Alternative names	ANZAC wafers, brewis, cabin bread, dog biscuit, hard tack, molar breakers, pilot bread, sea biscuit, sea bread, sheet iron, ship's biscuit, shipbiscuit, tooth dullers, worm castles
Type	Cracker or biscuit
Main ingredients	Flour, water

Hardtack (or hard tack) is a simple type of biscuit or cracker, made from flour, water, and sometimes salt. Inexpensive and long-lasting, it was and is used for sustenance in the absence of perishable foods, commonly during long sea voyages, land migrations, and military campaigns. The name derives from the British sailor slang for food, "tack". It is known by other names such as brewis (possibly a cognate with "brose"), cabin bread, pilot bread, sea biscuit, sea bread (as rations for sailors), ship's biscuit, or ship biscuit, or pejoratively as "dog biscuits", "molar breakers", "sheet iron", "tooth dullers", or "worm castles". Australian and New Zealand military personnel knew them with some sarcasm as ANZAC wafers (not to be confused with Anzac biscuit).

The introduction of the baking of processed cereals, including the creation of flour, provided a more reliable source of food. Egyptian sailors carried a flat brittle loaf of millet bread called dhourra cake, while the Romans had a biscuit called bucellatum. King Richard I of England left for the Third Crusade (1189–92) with "biskit of muslin", which was a mixed grain compound of barley, bean flour, and rye.

Some early physicians associated most medical problems with digestion. Hence, for sustenance and health, eating a biscuit daily was considered good for one's constitution. The bakers of the time made biscuits as hard as possible, as the biscuits would soften and become more palatable with time due to exposure to humidity and other weather elements. Because it is so hard and dry, hardtack (when properly stored and transported) will survive rough handling and temperature extremes. The more refined captain's biscuit was made with finer flour.