John Marshall (c.1784–1837) was a naval officer and biographer. He first went to sea at the age of nine, and by the end of the Napoleonic Wars in 1815 had reached the rank of lieutenant. After the war, he started to research the lives of contemporary high-ranking naval officers, some of whose service reached as far back as 1760. These volumes, first published between 1823 and 1830, contain the results of this monumental research, and demonstrate the new 'cult' of the navy in the early nineteenth century. Some of the biographies were contributed by the officers themselves, with others containing private or official letters and other records. Organised according to seniority in rank, these volumes contain a wealth of fascinating information on the careers of naval officers and the battles in which they took part. Part 4 of this Supplement contains biographies of Post-Captains, 1815–1822.