Bretagne was the offspring of an attempt to improve upon the by increasing the
beam from . The 1849 budget initially allowed for construction of a new three-decker capital ship named
Terrible in
Brest, but the ship was cancelled in 1848 to reduce expenses. The 1850 budget then scheduled two ships, named
Bretagne and
Desaix (in honour of
Louis Desaix), to be built in Brest and
Cherbourg respectively; the order was placed on 15 March 1851. The mediocre performances of during her
trials led to the Navy shedding the capital ship design of the
Commission de Paris and start back from
Jacques-Noël Sané's
Océan design, with only incremental modifications. In late 1851, engineers De Gasté, responsible for
Bretagne, and Forquenot, for
Desaix, decided on a reduction of the
tumblehome by and on a slight increase of the beam — alterations thought safe, as the two last ships of the
Océan design, and , had had their tumblehome reduced by with no ill effect. An initial suggestion to fit the ships with steam engines allowing for a speed of was declined as to minimise departures from Sané's design. ''.
Bretagne was
laid down on 4 August 1851 and
Desaix on 27 Octobre. On 17 June 1852, the Ministry of the Navy suspended construction and required that the ships be lengthened by and that steam engines be incorporated. Brest responded to the requirements in September 1852, but at the same point,
Dupuy de Lôme's fast ship of the line was completing her trials, exhibiting such outstanding performances that on 10 September 1852 the Ministry cancelled the
Bretagne class and ordered existing sailing ships to be converted to steamers, using as many existing parts as possible. At this point, the
keel,
bow and aft of
Bretagne had been erected, amounting to the third of the 24 construction steps defined by regulations in ship construction; she was taken apart and rebuilt according to Marielle's plans, which had been approved in December 1852. At the same time, the order for the steam engine was placed.
Desaix, whose keel was only beginning to be laid, was cancelled altogether and , second ship of the
Algésiras type, the production series of the
Napoléon design, was started instead. Launching of
Bretagne took place on 17 February 1855; in spite of a , snow and strong wind, a large populace gathered to watch the operation. The new design gave a length of and a beam of ; this made
Bretagne longer and wider than
Napoléon. With a
draught of , the ship had a volume of just under . The engine, provided by the , occupied a -long compartment and was designed for but could develop up to in peak power from eight boilers, each with six furnaces. Though direct transmission by an axis, it moved a four-blade, propeller which could be retracted into a vertical shaft, only wide thanks to the geometry of the blades. The ship carried 590 tonnes of coal, giving her an autonomy of 14 days at , and 6 days at her top speed of . With three months worth of food for the 1,200-man complement, and one month worth fresh water completed by a distillation device to desalinate seawater, she could stay at sea for 40 days. The main battery of
Bretagne used
36-pounder long guns, the heaviest available
calibre, instead of the more modern
30-pounder long gun on which other ships standardised their armament. The aft of the ship was round and featured gun ports, like on
Napoléon on her successors. Although she carried 130 guns of various calibres,
Bretagne featured no less than 180 gun ports; this allowed the crew to reinforce the artillery on one arc if needed and time permitting, such as before a shore bombardment, and fire up to 80 guns on one target. The
figurehead figured the prophet
Veleda, an important character in the folklore of
Brittany, with a sickle in hand and a wearing an oak leaf crown. The
transom featured the coat of arms of Brittany, carried by two
geniī, and the name of the ship underneath. The ship was painted in black, with white stripes along the level of the gunports and copper-red paint underwater. As completed,
Bretagne proved much heavier than anticipated: designed to displace 6,466 tonnes for an 8.20-metre draught, she actually displaced 6,873, yielding a 9-metre draught that lowered the lower battery to only above water, instead of the intended . of
Bretagne in Brest, circa 1860 The ultimate increase in French capital ship design,
Bretagne increased the number of heavy guns on the lower battery to 18 on each side, from the 15 of the of 1766 and 16 on the
Océans. In the original design, half of these guns were 36-pounder long guns, as to maximise firepower at the price of standardisation on 30-pounder long guns that typically prevailed at the time, the other half being 60-pounder
Paixhans guns. The middle deck fielded 18
30-pounder short guns and another 18 Paixhans guns of 60 pounds. The upper battery was armed with thirty-eight 30-pounder howitzers. Two 50-pounders and eighteen 30-pounder caronades complemented the armament on the deck. This gave
Bretagne a broadside of , compared to the of the original
Océan design. In 1869, after the ship became a school ship for the
École Navale, this armament was replaced with two rifled 19 cm guns on the lower deck; sixteen 30-pounder guns, four rifled 16-centimetre guns of the 1864 pattern, eight rifled 16-centimetre guns modified after the 1860 or the 1862 pattern, two muzzle-loading 16-centimetre rifled guns, and 2 14-centimetre guns on the middle battery; and 2 bronze 12-centimetre guns on the deck. == Operational history ==