Their role was to defend the mouth of the Gulf of Finland against the Germans, who never tried to enter, so the ships spent their time training and providing cover for minelaying operations.

Petropavlovsk was retained in commission to defend Kronstadt and Leningrad against the British forces supporting the White Russians although she also helped to suppress a mutiny by the garrison of Fort Krasnaya Gorka in 1919.

The two ships of the Baltic Fleet did not play a prominent role in the Winter War, but did have their anti-aircraft guns significantly increased before Operation Barbarossa in 1941.

The Navy took quite some time to absorb the design lessons from the war while the government reformed the Naval Ministry and forced many of its more conservative officers to retire.

[1] The requirements for a new class of dreadnoughts were in a state of flux during 1907, but Vickers Ltd submitted a design that met the latest specifications and was very nearly accepted by the Navy for a 22,000-long-ton (22,000 t) ship with twelve 12-inch (305 mm) guns in triple superimposed turrets.

The Naval Ministry defused the situation on 30 December 1907[Note 1] by announcing an international design contest with the ship built in Russia regardless of the nationality of the winning firm.

This was extended by a month to allow the Baltic Works to finalize its contract with the British firm of John Brown & Company for design assistance with the hull form and machinery.

However, after John Brown indicated that the ship's turbines could deliver 45,000 shaft horsepower (33,556 kW) if supplied with enough steam and that the hull form could reach 23 knots (43 km/h; 26 mph) with that amount of power, the Naval General Staff took the opportunity to get the speed it desired by using small-tube boilers.

Disadvantages were that the magazines had to be put in the middle of all the machinery, which required steam pipes to be run through or around them and the lack of deck space free from blast.

[12] Sixteen manually operated 50-caliber 4.7-inch (120 mm) Pattern 1905 guns were mounted in the hull in casemates as the secondary battery intended to defend the ship against torpedo boats.

The guns had a rate of fire of seven rounds per minute and a maximum range of about 16,800 yards (15,362 m) at 25° elevation with a 63.87-pound (28.97 kg) semi-armor-piercing Model 1911 shell at a muzzle velocity of 792.5 m/s (2,600 ft/s).

[15] Two Zeiss 5-meter (16 ft 5 in) rangefinders were fitted on the conning towers and there was also a 4.5-foot (1.4 m) Barr & Stroud instrument, possibly for precise stationkeeping on the master ship when concentrating fire.

A related weakness was that the turrets and conning towers lacked the inboard splinter bulkhead even though they used armor thickness roughly equivalent to that of the main belt.

[15] The waterline belt, made of Krupp cemented armor (KCA), had a maximum thickness of 225 millimeters (8.9 in), but tapered to about 150 mm (5.9 in) on its bottom edge.

And the lack of a splinter bulkhead behind the armor of the turrets, barbettes and conning towers left all of those locations vulnerable to main gun hits.

Once the Duma provided the funding the pace of work accelerated and the ships were launched later that year, although delays in the delivery of engines and turrets hindered their completion.

A minor mutiny broke out on 1 November on board Gangut when the executive officer refused to feed the crew the traditional meal of meat and macaroni after coaling.

[28] The crews of the battleships joined the general mutiny of the Baltic Fleet on 16 March 1917, after the idle sailors received word of the February Revolution in Saint Petersburg.

[30] On 17 August 1919 Petropavlovsk was claimed as torpedoed and put out of action by the British Coastal Motor Boat CMB 88 in Kronstadt harbor, but was, in fact, not damaged at all.

Subsequent plans that focused on reconstructing her as a modernized equivalent to her sisters or even as a battlecruiser, with one turret deleted to save weight, were considered, but finally abandoned on 23 January 1935 when all work was stopped.

[33] Parizhskaya Kommuna was refitted in 1928 in preparation for her transfer to the Black Sea Fleet the next year and she was given an open-topped false bow to improve her sea-keeping ability.

The rest of her modernization was along the same lines as Marat's, except that the latter's tubular foremast was replaced by a sturdier semi-conical mast, a new aft structure was built in front of the rear conning tower which caused the mainmast to be moved forward, her forward funnel was curved to the rear to better keep the bridge clear of exhaust gases and the thickness of her turret roofs was increased to 152 millimeters (6.0 in).

She completed these alterations in 1938, but was returned to the dockyard from December 1939 through July 1940 to receive a new armored deck and anti-torpedo bulges which cured her stability problems and greatly increased her underwater protection at a modest cost in speed.

[34] The participation of Marat and Oktyabrskaya Revolyutsiya in the Winter War was limited to a bombardment of Finnish coastal artillery in December 1939 at Saarenpää in the Beryozovye Islands before the Gulf of Finland iced over.

[35] On 22 June 1941, the Germans attacked the Soviet Union under the codename of Operation Barbarossa; on that date Marat was in Kronstadt and Oktyabrskaya Revolyutsiya was in Tallinn.

[41] Parizhskaya Kommuna was in Sevastopol and remained until 30 October 1941 when she was evacuated to Novorossiysk after the Germans had breached Soviet defensive lines near the Perekop Isthmus.

[43] By the time this was finished the Soviets were unwilling to expose such a prominent ship to German air attacks, which had already sunk a number of cruisers and destroyers.

She returned to her original name on 31 May 1943, but remained in Poti until late 1944 when she led the surviving major units of the Black Sea Fleet back to Sevastopol on 5 November.

[44] After the war there were several plans, known as Project 27, to reconstruct Petropavlovsk (ex-Marat), using the bow of Frunze and moving her third turret to replace the first, but they were not accepted and were formally cancelled on 29 June 1948.

[45] After World War II two of Frunze's turrets and their guns were used to rebuild the destroyed Coastal Defense Battery 30 (Maxim Gorky I) in Sevastopol.