The "seventy-four" was a type of two-decked sailing ship of the line, which nominally carried 74 guns. It was developed by the French navy in the 1740s, replacing earlier classes of 60- and 62-gun ships, as a larger complement to the recently-developed 64-gun ships. Impressed with the performance of several captured French seventy-fours, the British Royal Navy quickly adopted similar designs, classing them as third rates. The type then spread to the Spanish, Dutch, Danish and Russian navies. The design was considered a good balance between firepower and sailing qualities. Hundreds of seventy-fours were constructed, becoming the dominant form of ship-of-the-line. They remained the mainstay of most major fleets into the early 19th century. From the 1820s, they began to be replaced by larger two-decked ships mounting more guns. However some seventy-fours remained in service until the late 19th century, when they were finally supplanted by ironclads. Standardising on a common ship size was an appealing ideal for naval administrators and bureaucrats. Although the seventy-four was a common type, the ship classes were not identical, even within the same navy. In the period 1750–1790, seventy-fours could measure from just under 2,000 to 3,000 tons burthen. The armament could also vary considerably, with the lower deck mounting 24-pounder to 36-pounder long guns, and a variety of calibres (sometimes including a few carronades) used on the upper deck. Some seventy-fours of the Danish navy only carried 70 guns. First 74-gun designs The first 74-gun ships were constructed by the French as they rebuilt their navy during the early years of the reign of Louis XV. The new ship type was a very large two-decker big enough to carry the largest common type of gun (36-pounders) on the lower gun deck, something only three-deckers had done earlier. This great firepower was combined with very good sailing qualities compared to both the taller three-deckers and the shorter old-style 70-gun two-deckers, making the 74 the perfect combination of the two. A disadvantage of the 74 was that it was relatively expensive to build and man compared to the older type of two-decker. The 74-gun ship carried 28 (24-pounders- to 36-pounders) on the lower gun deck, 28–30 (18- to 24-pounders) on the upper gun deck, and 14–18 (6- to 12-pounders) on the upper works. Crew size was around 500 to 750 men depending on design, circumstances and nationality, with British ships tending to have smaller crews