The classic British soldier Biscuit (hardtack) was pretty similar. This recipe makes ONE biscuit. Scale it up or down as needed.
2 cups flour
1/2 tablespoon salt
1/2 cup water
Mix all ingredients well. Add a little extra water if needed (a teaspoon at a time) until you have a very stiff (not sticky) dough. Work the dough into a ball, then set it aside for a fre minutes to let it set up. Next, roll the dough ball out until it is about 3/8 of an inch thick, cut it and punch 12 to 16 holes into each round to help let the moisture escape. Place a few clean bricks in your oven and preheat it to 350-400 degrees, then place your biscuits on the bricks for one-half hour or until all the moisture is out of them and they are slightly browned (you can use a cookie sheet instead of bricks, though the later will give you a better biscuit). Finally, set your biscuits aside to cool and dry out for a day or two. Biscuits must be dry and hard in order to keep well. Two of these make up a pound of "bread".
This is the recipe from Mark Tully's booklet The Packet, and is based upon the early to mid 1700's military records. Two of these biscuits were the bread portion of the daily military issue ration for a soldier/sailor. The daily ration was one pound of bread, one pound of beef or pork, just over an ounce of rice, seven ounces of peas, and just under one ounce of butter. But the rations were generally issued once a week.
Adding anything like sugar or butter or anything else will greatly reduce the "shelf life". Those other things tend to lead to mold growth. Ship's biscuit or hardtack was meant for long term storage - as long as you kept it dry. Hmmm ... one ship like the HMS Victory carrying 500 plus men, each getting 2 ship's biscuits a day, and being out of port for several months. That's a lot of biscuits to have made up and stored below deck! 1000 a day is 500 pounds per day, times how many days?
One friend makes up his Ship's Biscuits for living history camps following this recipe. But he also adds in a small handful of uncooked brown rice to the dough. Then, when he is "in camp" in front of the public, he can ... pick out "weevils" from his issued biscuits! (but they also don't hurt him to just eat them) Yeah, he does have a bit of a twisted mind. But the looks he gets from the spectators is wonderful!
Mikey - that grumpy ol' German blacksmith out in the Hinterlands