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. But by the French Revolutionary and Napoleonic Wars, even this function