Hard tack

Hard tack was used during long sea voyages and military campaigns as a primary foodstuff usually dunked in water, brine, coffee or some other liquid or cooked into a skillet meal. This cracker was little more than flour and water which had been baked hard and would keep for months as long as it was kept dry. Also known as a sea biscuit, sea bread, or ships biscuits.

A basic recipe follows:
2 cups of flour
1/2 to 3/4 cup water
6 pinches of salt
Some recipes add 1 tablespoon of Crisco or vegetable fat

Mix all the ingredients into a batter and press onto a cookie sheet to a thickness of 1/2 inch. Bake in a preheated over at 400 degrees for one hour. Remove from oven, cut dough into 3-inch squares, and punch four rows of holes, four holes per row into the dough (a fork works nicely). Flip the crackers and return to the oven for another half hour.

Some recipes also recommend a second baking at 250 degrees to thoroughly dry out the bread.