12-pounder long gun

The 12-pounder long gun was an intermediary calibre piece of artillery in [the Age">naval artillery in the Age of Sail">artillery in [the Age of Sail|artillery] mounted on warships of the Age of Sail. They were used as main guns on the most typical frigates of the early 18th century, on the second deck of fourth-rate ships of the line, and on the upper decks or castles of 80-gun and 120-gun ships of the line. Naval 12-pounders were similar to 12-pound Army guns in the Gribeauval system: the canon lourd de 12 Gribeauval, used as a siege weapon, and the canon de 12 Gribeauval, which was considered a heavy field artillery piece.

Usage

As the 12-pounder calibre was consistent with both the French and the British calibre systems, it was a widespread gun amongst nations between the 17th and the 19th century. From the late 18th century, the French Navy used the 12-pounder in three capacities: as main gun on early frigates under Louis XIV, on standard frigates under Louis XV and on light frigates under Louis XVI; as secondary artillery on 64-gun ships; to arm the castles of 80-gun ships of the line; and to equip the third deck of early first-rate ships.
Under Louis XIV, frigates were organised into "first-rank frigates", which were small two-deckers comparable in role to the 60-gun ships of the 19th century, and smaller "second-rank" frigates. The first-rank frigates carried the 12-pounder as main artillery on their lower deck. Later, under Louis XV, the frigate took its modern shape with a single artillery deck complemented by smaller pieces on the castles; new heavy frigates were developed to carry 26 12-pounders, with as the lead ship of the series. Hermione was captured by the British in 1757 and was swiftly imitated. A breakthrough towards fielding heavier guns was made in 1772, when the two units of the were built, with 24-pounders intended, but 18-pounders used in practice, and the 12-pounder remained the standard issue on most units. Under Louis XVI, the heavier 18-pounder frigate became predominant, with over 130 units produced, but the French Navy still had around 70 lighter 12-pounder frigates in commission.
On 64-gun two-deckers, the 12-gun was used as secondary artillery, to supplement the 24-pounder main batteries. 28 guns were carried on the top gun-deck.
Larger units used the 12-pounder to complement the firepower provided by their main and secondary artillery. On 80-gun ships of the and, they armed the forecastle and the poop deck. On capital ships, the 12-pounder was used on the third deck from the reign of Louis XIV, with units like or as typical examples. While the secondary artillery of these 100-gun ships evolved from 18-pounders to 24-pounders, the 12-pounder remained the standard gun on the third deck until 1803, when the ship Impérial became the first 120-gun to carry 18-pounders on her third battery.
In the Royal Navy, the 12-pounder was used in a similar capacity. The capture of Hermione in 1757 encouraged the British to imitate her design, yielding the and frigates. The 12-pounder also equipped the castles on razeed ships, where 12 pieces were mounted, and the 22-gun secondary battery of 50-gun fourth-rates. Finally, 30 were installed on the third deck of 90-gun second-rates.

British iron 12-pounders

Early iron 12-pounders

James mentions 4 12-pounder iron guns in the 1720s. Their length varied from 8 1/2 ft to 10 ft, in 6 in increments. 24 guns from the reigns of Queen Anne and King George I survive at Fort Prince of Wales in Hudson bay. They are either 9 1/2 ft long weighing between 33 1/2 and 35 cwt, 9 ft long weighing between 32 and 33 1/2 cwt, or 8 ft long weighing 33 1/4 cwt. The mensuration of 1743 gives the weight of the 9 ft 12-pounder gun as 32 hundredweight 2 quarter 3 pounds, and the dimensions there are almost identical with those in Adye's notebook of 1766. In 1780 Walton's notebook mentions, in addition to newer 12-pounders, a 9 1/2 ft gun of 34 hundredweight. The dimensions of this are very similar to those of Armstrong's construction in the early 1700s. Based on these sources, the iron 12-pounders in the early 1700s had the following specifications:

Gun Length	Weight	Notes
10	?
9 1/2	34	Based on Walton's notebook in 1780
9	32 1/2, 3 lb	Based on mensuration of 1743
8 1/2	?
8	33 1/4	Based only on a single gun from Fort Prince of Wales

The establishment of 1764 specifies 3 types of iron 12-pounder guns:

Gun Length	Weight
9	32 1/2
8 1/2	31 1/2
7 1/2	29 1/4

Walton gives dimensions for these guns in his 1780 notebook, and where known, they are very similar to the earlier guns, with only minor differences.

Blomefield's 12-pounders

developed several iron 12-pounders as part of his system of gun construction from the 1790s onward:

Gun Length	Weight	Method of construction	Uses
9	34 3/4	newly cast	chase guns, line of battle ships, garrison
8 1/2	33 1/4	newly cast	garrison service, battering train
7 1/2	29 1/4	newly cast	quarter deck, line of battle ships, garrison
6	24	newly cast	Not used, sometimes bored-up to 24-pounder 22 cwt
6	21	newly cast	Sometimes bored-up to 24-pounder 21 cwt

Both guns of 6 ft were intended exclusively for the land service, and by 1857 the gun of 6 ft 21 hundredweight was the only one mounted in service, presumably in the defense of ditches. The gun of 8 1/2 ft 33 1/4 hundredweight was recommended for siege trains in 1844, as it could dismount artillery while requiring less weight of ammunition and powder than an 18- or 24-pounder gun. At the same time, the gun of 9 ft 34 3/4 hundredweight was recommended for sometimes replacing the 18-pounder in batteries where quick fire was required against storming parties or boat attacks. After the 1820s, the development of larger guns meant the iron 12-pounder declined in use, and in 1859 the Committee on Ordnance recommended that all iron 12-pounders except the gun of 6 ft be declared obsolete. In 1865 though, the guns of 9 and 8 1/2 ft were retained while all others were declared obsolete.