12-pounder long gun

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 Hermione as lead ship of the series. Hermione was captured by the British in 1757 and was swiftly imitated. Breakthrough towards fielding heavier guns were made in 1772, when the two units of the Pourvoyeuse class 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 Tonnant class and Bucentaure class, 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 Royal Louis or Soleil-Royal 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 Océan class 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 Southampton class and Richmond class 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.

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