Ship's Biscuit was one of the staples of Naval cuisine, at least for the enlisted man (Jane Austen mentions that her mother preserved several hams for her sea bound officer son to take with him...) This type of food, however, would have been no stranger to the sea faring Austen brothers. Made of flour, salt and water, they were baked up to four times, to ensure that any excess moisture was removed, allowing the bread to last indefinitely. At the time of the Spanish Armada in 1588, the daily allowance on board a Royal Navy ship was one pound of biscuits plus one gallon of beer. Later, Samuel Pepys in 1667 first regularised naval victualing with varied and nutritious rations. Royal Navy hardtack during Queen Victoria's reign was made by machine at the Royal Clarence Victualing Yard at Gosport, Hampshire, stamped with the Queen's mark and the number of the oven in which they were baked. Biscuits remained an important part of the Royal Navy sailor’s diet until the introduction of canned foods; canned meat was first marketed in 1814, and preserved beef in tins was officially introduced to the Royal Navy rations in 1847. Ship's biscuit, crumbled or pounded fine and used as a thickener, was a key ingredient in New England seafood chowders from the late 1700s onward. In 1801, Josiah Bent began a baking operation in Milton, Massachusetts, selling "water crackers" or biscuits made of flour and water that would not deteriorate during long sea voyages from the port of Boston, which was also used extensively as a source of food by the gold prospectors who emigrated to the gold mines of California in 1849. Since the journey took months, pilot bread, which could be kept a long time, was stored in the wagon trains. His company later sold the original hardtack crackers used by troops during the American Civil War. The G. H. Bent Company remains in Milton, and continues to sell these items to Civil War re-enactors and others. The following video demonstration from Jas. Townsend and Son provides a period look at baking Ship's Biscuits, along with some historical information and a recipe for creating your own.
Historical information from Wikipedia.com