Half pay (h.p.) was a term used in the British Army and Royal Navy of the 18th, 19th and early 20th centuries to refer to the pay or allowance an officer received when in retirement or not in actual service.
The maritime adventure novels of the Horatio Hornblower series, set during the Napoleonic Wars, include numerous references to the protagonist and his fellow naval officers' fear of being retired and "stranded ashore on half-pay" which they consider as their worst nightmare. The reason being that even full-pay was often barely sufficient to cover the living expenses of an officer and any dependents. In addition to the permanent retirement of individuals, peacetime cut-backs in the wartime establishments of both army and navy could mean significant numbers of serving officers being placed on half-pay while awaiting new appointments which might not eventuate.