4th rate

A fourth-rate was, in the British Royal Navy during the first half of the 18th century, a ship of the line mounting from 46 up to 60 guns. While the number of guns stayed subsequently in the same range until 1817, after 1756 the ships of 50 guns and below were considered too weak to stand in the line of battle, although the remaining 60-gun ships were still classed as fit to be ships of the line. However, the 50-gun ship continued to be used largely during the Seven Years' War, and during the time of the American Revolution a whole new group of 50-gun ships was constructed, not for the battlefleet, but to meet the needs of combat in the shallow waters off North America where the larger ships found it difficult to sail. 50-gun ships were also suitable as convoy escorts and for service on foreign stations, where larger enemy vessels were unlikely to be encountered. Some saw service as flagships since, as two-deckers, they were able to accommodate a flag officer and his retinue, and they also had the physical presence of a flagship. Their usefulness was declining, however, and during the French Revolutionary and Napoleonic Wars few 50s were built, although several remained in service, especially on distant stations such as the East Indies. The 60-gun ships were also dying out, superseded initially by the 74-gun third-rates, although by 1793 there were still four 60-gun ships left in harbour service.

Some fourth-rates did remain in active service even during the Napoleonic Wars, especially in the shallow North Sea, where the Royal Navy's main opponents were the Baltic powers and the Dutch, whose own fleet consisted mainly of 50- to 64-gun ships (e.g. the 56-gun Delft). However, HMS Leander, 50 guns, was with Horatio Nelson at the Battle of the Nile. As late as 1807, fourth-rates were active in combat zones, illustrated by the fatal incident between HMS Leopard (50 guns), and the US frigate Chesapeake (38 guns), an incident which nearly led to war.

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