During the First World War in Great Britain, submarines were called submarines, which were armed with powerful artillery weapons. The idea of creating such a ship, the main weapon of which would not be torpedoes, but artillery, was in the air from the very beginning of the active use of submarines. The farthest along this path went the British, who in 1916-1919 developed a series of submarines armed with large (battleship) caliber artillery. These ships went down in history as underwater monitors of the "M" type.
It is worth noting that in history there were other projects for the construction of artillery submarines, but it was the models proposed by the British Admiralty that rightfully became the champions in terms of the caliber of the installed artillery - 305 mm. At the same time, the most powerful submarine built with artillery weapons remained the French submarine "Surkuf", armed with two 203-mm artillery pieces. The boat, built before the Second World War, although it was an interesting project, was inferior in its capabilities to both classic submarines and classic cruisers.
Gloomy British genius
Despite the fact that the boats could not demonstrate the capabilities of their powerful weapons in battle, and their very combat value turned out to be practically zero, underwater monitors were rightly attributed to the unique creations of British engineering. The main purpose of the British underwater monitors was coastal patrolling and the stealthy bombardment of enemy ships, as well as coastal facilities and fortifications with powerful artillery. At the same time, the British were seriously afraid of the fact that the Germans would be the first to develop such boats, which would create serious problems for Great Britain. True, the Germans did not even hatch such plans, which the Admiralty simply did not know about.
The idea of creating submarines armed with powerful artillery weapons was first announced in Great Britain in the second half of 1915. In many ways, such a project was born due to the low efficiency and reliability of British torpedoes of that time period. Torpedo tubes and the torpedoes themselves were unreliable weapons. As the British themselves joked, English torpedoes could do everything except the main thing - to sink enemy ships. Often torpedoes floated to the surface and enemy ships easily dodged them, often on the contrary they went into the depths, often the torpedoes simply broke into pieces. And even when hitting the target, the torpedoes did not always explode, which frustrated such rare successful attacks. It was in this environment that the British decided to create their underwater monitors, armed with powerful 305-mm guns taken from the decommissioned battleship Majestic.
Naturally, British engineers and admirals considered different options for artillery weapons. Already during the First World War, submarines with powerful weapons, for example, 120-mm guns, were born. Against this background, the idea of installing battleship guns on a submarine even then looked utopian. Prior to that, the E-20 submarine, armed with a 152-mm cannon, could boast of the largest caliber, and German submarines with two 150-mm guns were only at the construction stage. Against this background, the Admiralty considered the option of creating a submarine armed with two 190-mm guns. But, as subsequent events showed, it was impossible to fit two 190-mm guns on the submarine at once, so it was decided to limit itself to one gun, but immediately 305-mm. For the most part, the Admiralty did not discuss the caliber of the gun itself for a longer time, but the questions of whether a similar submarine is needed by naval sailors and how it would be possible to use such an underwater monster.
The main reasons for building underwater monitors were as follows. First, as noted above, the existing torpedo armament was unreliable, and the torpedo attack itself is a very difficult task, even with the correct calculations, the boat's crew could fail the equipment. Secondly, the submarine could take on board a much larger stock of 305-mm shells than torpedoes. Thirdly, having unexpectedly surfaced in front of the enemy, the boat could be guaranteed to hit the enemy with its heavy artillery weapons, the latter simply would not have had time to maneuver. As a result, the concept of creating an M-type underwater monitor was accepted, and the Admiralty issued an assignment for the construction of the first four ships.
Submarines were not built from scratch. The largest at that time British submarines of the K type were taken as the base. The Vickers company was ordered to convert the K18-K21 submarines into underwater monitors M1, M2, M3 and M4, respectively. The last four K-type submarines were ordered in February 1916, by which time the technical documentation for the new submarine warships was ready. The slipway work had not yet begun when the final decision was made to convert the boats into M-type underwater monitors.
Technical features of M type underwater monitors
The M-type submarines were based on a deeply revised project of large British K-type submarines, which, during two years of operation, did not prove themselves to be the best, the British sailors had a lot of complaints about these submarines. The main problem with K-type submarines was their steam turbine power plant. The power plant was so unreliable that it often disabled warships, forcing them to get up for lengthy repairs, and in some cases it caused the death of the boats along with the crew. Taking into account the negative experience, the M-type underwater monitors were immediately developed for the installation of a diesel-electric propulsion system. It is this option that will become the main one in the fleets of various countries for many decades and the only one before the appearance of the first submarines with a nuclear power plant.
The strong hull of the new submarines was made of steel with a thickness of 14 and 15.9 mm in the middle part of the hull, becoming thinner towards the ends, the light hull was made of steel with a thickness of 6, 4 to 19 mm. All M-type underwater monitors were one-and-a-half hull boats with a design depth of 60 meters. The boats had to go to the periscope depth in 90 seconds. The strong hull of the submarine was divided by bulkheads into 11 compartments. The immersion and ascent system included 20 external ballast tanks at once, the designers placed them on the sides of the boat. The total capacity of the ballast tanks was 375 tons. Surface displacement of boats reached 1594 tons, submarine - 1946 tons. The maximum length of monitors was 90, 15 meters, diameter - 6, 2 meters, draft - 3, 56 meters.
The advent of a diesel-electric power plant made the boat and its crew safe. Compared to the steam turbine in K-boats, this was a step forward. On the underwater monitor, the designers placed two diesel engines for surface movement and four electric motors for underwater propulsion. Vickers was responsible for the development of diesel engines. The boats were equipped with four-stroke 12-cylinder diesel engines with a capacity of 1200 hp. each. For the underwater movement, four electric motors with a capacity of 800 hp were used. each. The motors of the underwater monitor set in motion two three-blade propellers, the diameter of which reached 1.78 meters. The power plant was considered powerful enough and provided unusual ships with a good surface and underwater speed. In the surface position, the monitors could accelerate to 15 knots (almost 28 km / h), in the submerged position the speed was 8-9 knots (up to 16, 5 km / h). On the surface, moving at an economic speed of 10 knots, the ship could overcome 4500 nautical miles (approximately 8300 km) without refueling. In a submerged position, the monitors could cover no more than 150 km.
The 305-mm gun was placed in front of the sub's wheelhouse. Initially, it was planned to make the artillery installation waterproof and armored, but over time this idea was abandoned. Only the charging chamber remained waterproof. The weight of the entire installation, together with the gun, reached 120 tons, the mass of the ammunition, which consisted of 40 shells, was another 29 tons. A 305-mm gun with a barrel length of 40 calibers made it possible to fire at targets at a distance of 19 km. The rate of fire of the gun was low - one shot every 75 seconds. At the same time, the angles of horizontal guidance of the gun were only 15 degrees, the elevation angle was 20 degrees, the gun was lowered down by 5 degrees. Additional artillery armament was the 76-mm Mk II cannon, which was located at the stern of the monitor and made it possible, among other things, to fire at aerial targets. The designers retained the torpedo armament, which was represented by 4x450-mm torpedo tubes, the boat's ammunition consisted of 8 torpedoes.
The crew of the M-type underwater monitors included 65 people, including 6 officers and 59 petty officers and sailors. Since the ship was a specific submarine, a very large part of the crew was engaged in artillery armament maintenance. In the gun mount, the 305-mm cannon was serviced by 11 people, 16 more sailors worked in the cellar and on the supply of shells, 4 gunners made up the calculation of the 76-mm stern cannon, two more sailors had to bring them shells.
Type M underwater monitors were considered comfortable for crew work and rest by ships. The boats were large and had a diesel-electric power plant instead of steam boilers and turbines on Type K boats. At the same time, the crews were glad that the ship had ceased to be overwhelmed by waves through openings and pipes for air access, as was the case on the submarines mentioned above. Another advantage of the ships was that during the shift duty, the sailors on the bridge remained dry in almost any weather, which was very unusual for submarines of that time. The sailors were protected by a developed superstructure and a 305-mm gun, which served as a kind of breakwater and prevented the wave from overwhelming the bridge.
The fate of M-type underwater monitors
The lead ship of the series, the M1 underwater monitor, was laid down by Vickers in June 1916. The launching of the new warship took place on July 9, 1917, and commissioning took place on April 17, 1918. The boat was ready by the very end of the First World War, but the British command was not eager to test the ship in combat conditions. Instead of battles in the North Sea, the underwater monitor was sent to the Mediterranean Sea, where it never met the enemy. The fate of the M1 underwater monitor ended tragically. The boat died in peacetime along with the entire crew, in 1925 in the Plymouth area she collided with a Swedish steamer and sank.
The M2 underwater monitor was laid down in July 1916, and launched at the very end of World War I, on October 19, 1918. The unusual ship entered service after the end of the conflict - on February 14, 1920. In 1925, the M2 underwater monitor underwent a major upgrade and was rebuilt into a submarine aircraft carrier. In this capacity, the ship was used quite fruitfully until January 26, 1933. On this day, the boat sank at a depth of 32 meters near the Cesil beach, killing the entire crew. A later survey showed that the hangar hatch was open on the boat. Most likely, the boat was depressurized by mistake, but what exactly led to such sad consequences remained unclear. This warship has become a true long-liver of the entire series, having served in the Royal Navy until the moment of the tragedy for almost 13 years.
The M3 underwater monitor was laid down in December 1916 and launched on October 19, 1918. The ship entered service after the end of the First World War on July 9, 1920. The entire service of the ship was completely unremarkable. In 1927, the British Admiralty decided to convert the ship into a large underwater minelayer. The dismantling of the 305-mm gun mount and the alteration of the superstructure made it possible to place 100 Mk-type sea mines on board the submarine at once. 5. Service of the boat proceeded without any special incidents and ended in 1932, when the ship was scrapped.
The M4 underwater monitor was laid down on December 1, 1916 at the Armstrong Whitworth shipyard. The boat was launched after the First World War - on July 20, 1919, and it was decided not to finish building it. After the cancellation of construction, the ship was simply dismantled for scrap.
Summing up the program for creating M-type underwater monitors, it can be noted that, despite the original technical solutions, the boats were not in demand by the military and did not have any impact on the course of the First World War at sea. The M1 monitor was used only for patrol functions and never used its main caliber for its intended purpose. From the entire series of underwater monitors, three boats were completed. Of these, only two ships, after serious modernization, could be used quite productively in military service.
