| Is Artillery: | yes |
| Is Uk: | yes |
| 24-pounder long gun | |
| Type: | Naval gun |
| Used By: | France, Spain, Great Britain, Netherlands, Sweden, United States |
| Caliber: | 152.2 mm[1] |
| Part Length: | Approx. 3 metres |
| Weight: | 2,500 kg 470 kg (mount) |
| Cartridge Weight: | 11.7 kg |
| Crew: | 12 gunners and one powder-boy |
| Unit Cost: | 1252 Francs |
The 24-pounder long gun was a heavy calibre piece of artillery mounted on warships of the Age of Sail. 24-pounders were in service in the navies of France, Spain, Great Britain, the Netherlands, Sweden, and the United States. They were comparable to the Canon de 24 Gribeauval used by the French Army as its largest piece of siege artillery. 24-pounders were used as main guns on the heaviest frigates of the early 19th century and on fourth-rate ships of the line, on the second deck of first-rate ships of the line, and on the second deck of a few large third-rates.
The 24-pounder calibre was consistent with both the French and the British calibre systems, and was a widespread gun amongst nations between the 17th and the 19th century.
From the late 18th century, the French Navy used the 24-pounder in two capacities: as main gun on frigates and 64-guns, or as secondary artillery on three-deckers and even enlarged versions two-deckers. Under Louis XV, a typical heavy frigate would carry 12-pounder long guns until 1772, when the two vessels of the were built to carry 24-pounders; these proved too heavy in practical use, however, and the vessels were re-equipped with 18-pounders, heralding the coming of the 18-pounder frigate that would become the standard in many navies of the late 18th century. The experiment was tried again in 1785 with, a successful design that opened the way to a standardisation on the 24-pounder frigate exemplified by the . Overall, 14 of these heavy frigates were built between Pomone in 1785, and in 1798, each carrying between 24 and 30 24-pounders. After the Bourbon Restoration, frigates were built using a different artillery system, carrying 30-pounders.
Two-deckers used the 24-pounder in two capacities: on the smallest two-deckers of 64 guns, the 24-pounder constituted the main artillery, with 26 pieces. Typical 74-gun vessels carried a 36-pounder main battery and an 18-pounder secondary battery, until the enlarged variant of the appeared in 1803, comprising and . More significantly, the 24-pounder armed the secondary battery of all 80-gun ships of the line from 1749, when the introduced the practice,[2] resulting in a two-decker with enough firepower to challenge a three-decker of the time.
During the reign of Louis XIV, three-deckers were standardised on a 36-pounder main artillery and an 18-pounder secondary battery. From the mid-18th century, under Louis XV, the secondary battery was strengthened to 24-pounders, beginning with the design that yielded . The other capital ships of the era,, flagship of François Joseph Paul de Grasse during the American War of Independence, and, flagship at the Battle of Ushant, similarly carried 24-pounders as secondary batteries. The practices was continued with the and the . During the First French Empire, 24-pounders would also arm Type 1 Model Towers for coastal defence.
In the Royal Navy, the 24-pounder was similarly used on some heavy frigates, which carried 26 guns. Fourth-rate ships carried 22 on their secondary batteries, and third-rates carried 32. First-rates carried thirty-four 24-pounders on their middle deck.
Four lengths of iron 24-pounders are mentioned in a notebook from the 1720s:,,, and long. Ten surviving guns which are likely examples of the 9-foot version weigh between 48 and 49 hundredweight. These guns are very similar to the gun of 9 feet and 49 hundredweight which was detailed in the mensuration of 1743.
In the establishment of 1764, two new iron 24-pounders were specified (1 source specifies both guns were 9 feet long, but this is likely an error):
| Length (ft) | Weight (cwt) | |
|---|---|---|
| 9 1/2 | 49 | |
| 9 | 47 1/2 |
Sir Thomas Blomefield developed several iron 24-pounders as part of his system of gun construction from the 1790s onward:
| Gun length (ft) | Weight (cwt) | Date first cast | Method of construction | |
|---|---|---|---|---|
| 9 1/2 | 50 1/2 | 1790s | newly cast | |
| 9 | 47 3/4 | 1790s | newly cast | |
| 8 | 43 | 1813 | newly cast | |
| 7 1/2 | 40 | 1813 | newly cast | |
| 6 1/2 | 33 | 1805 | newly cast | |
| 6 | 30 | 1800 | newly cast | |
| 8 | 37 | before 1847 | bored-up from Blomefield 18-pounder 38 cwt | |
| 6 | 22 | before 1865 | bored-up from Blomefield 12-pounder 24 cwt | |
| 6 | 20 | before 1865 | bored-up from Blomefield 12-pounder 21 cwt |
In response to a desire for lighter 24-pounders that could still be double-shotted, William Congreve designed a radical new type of 24-pounder, which was shorter, lighter, and with more metal concentrated around the gun breech rather than the chase (gun barrel). It had a muzzle similar to a carronade, and the breeching ring was discarded in favor of a hole in the center of the neck of the cascabel. Because the weight of the cannon was much farther back, the trunnions could also be cast much farther rearward than in a similar conventional cannon. Initially two guns were manufactured for testing:
| Length (ft) | Weight (cwt) | |
|---|---|---|
| 7 1/2 | 41 | |
| 7 1/2 | 37 |
In 1853, the Aide-Mémoire mentioned 2 designs by Millar:
| Length (ft) | Weight (cwt) | |
|---|---|---|
| 7 1/2 | 41 | |
| 6 1/2 | 33 |
In addition, a number of guns designated "N.P." for New Pattern appear in the records of the Committee on Ordnance. These have lengths of 9, 9, 8,,, and, but no other details are mentioned. Finally, a 24-pounder of either or and 18 cwt was mentioned, and it was declared obsolete in 1865 by the War Department.
Images are available showing 24-pounder long guns as the main gun deck armament on the as used during the American Revolution; and the USS Constitution and USS Constellation as two of the original six frigates of the United States Navy starting in 1797.
From the War of 1812 until the 1840s, The U.S. Navy used three classifications: the gun proper, which had a barrel weight of per pound of shot, the double-fortified gun which had a barrel weight of per pound of shot, and the medium gun, which had a barrel weight of per pound of shot. By comparison, a carronade would have a barrel weight of per pound of shot.[4]