The first specialized means of dealing with enemy submarines already during the First World War were depth charges. Having found a submarine, a ship with such a weapon had to drop special high-explosive ammunition on it. Nevertheless, in a number of cases the use of such weapons was excluded. Taking into account the needs of the fleet, British engineers created several anti-submarine howitzers, including the BL 7.5-inch naval howitzer.
The main problem with depth charges was the specific requirements for the carrier. The ship or boat, armed with them, had to be distinguished by high speed and maneuverability. Thus, large warships or transports, in need of protection, could not use powerful and effective weapons. This problem could be solved by organizing a cover, but this led to known difficulties. The way out of the situation could be some kind of weapon capable of solving combat missions, regardless of the characteristics of the carrier ship.
General view of the BL 7.5-inch naval howitzer
No later than the end of 1916, a proposal appeared that, as it seemed then, could help the military and merchant navy. Specialists of the maritime department proposed to equip ships and vessels with a special weapon optimized for the needs of anti-submarine defense. Soon the first project of such a system was developed, which received the symbol BL 5-inch naval howitzer ("Breech-loading 5-inch naval howitzer").
The new project was based on the idea of hitting the submarine with a blast wave from a high-explosive projectile of high power. The high power of the projectile needed to be supplemented with a sufficient firing range. Finally, a new pedestal unit was needed. Some of the tasks could be solved using the components of the ground howitzers of the appropriate caliber. By the beginning of 1917, one of the British enterprises received an order to convert a dozen land howitzers into anti-submarine weapons.
At the very beginning of 1917, 12 BL 5-inch naval howitzer systems passed the necessary tests. Working at the test site, these products, in general, confirmed the viability of the original idea. However, there were serious shortcomings. The 127-mm high-explosive howitzer projectile carried an insufficient explosive charge. As a consequence, the real power when firing at the submarine was insufficient. The inability to obtain the desired combat characteristics led to the abandonment of the 5-inch howitzer and the start of the development of a new system of increased caliber.
One of the serial 7.5-inch (190 mm) guns was taken as the basis for the new system. As a result, a promising anti-submarine howitzer was named BL 7.5-inch naval howitzer. Also, from a certain time it began to be designated as Mark I, which indicated the possible development of the project in the future.
The first project involved the use of a shortened barrel of the production model. The fact is that the existing British 190-mm guns were distinguished by a fairly long firing range, which simply exceeded the visual detection distance of the submarine. As a result, for installation on a new carriage, the existing rifled barrel had to be shortened to 1.62 m, taking into account the chamber (in total, 8.5 caliber). This made it possible to reduce the initial velocity of the projectile in an acceptable way and reduce the firing range to a practically usable level.
The short rifled barrel was equipped with a reduced chamber for a reduced propellant charge and was equipped with a piston bolt that was locked by turning around its axis. On the breech of such a howitzer, mountings were provided for the installation of sighting devices. A characteristic feature of the BL 7.5-inch naval howitzer project was the absence of recoil devices. The entire recoil impulse was to be transmitted to the pedestal installation, and then to the deck and the carrier's power set.
An original column mount was developed especially for anti-submarine howitzers. According to some reports, the main aspects of its appearance were determined in the first project, and when creating a 7.5-inch system, the existing structure was modified taking into account new loads.
Anti-submarine howitzer aboard the SS Boohan
On a suitable section of the carrier ship's deck, it was proposed to mount a large and powerful installation of a complex shape. Its lower unit was a circular support platform, which consisted of a pair of flat parts. Along the perimeter of the platform, there were many holes for fastening screws. The absence of recoil devices has led to the need to use the most durable support. The center of the platform had a kind of shoulder strap. Inside it there was a rail for moving the gun mount. The displacement of the latter was prevented by a clamping ring.
On the platform, a U-shaped pedestal was installed movably, with the possibility of turning around a vertical axis. In its upper part there were supports for the trunnions of the tool cradle. The barrel was mounted on the unit using a small rectangular cradle with pins on the sides. Nearby there was a screw mechanism for vertical guidance.
A vertical support was placed on the upper part of the cradle, which was used as part of sighting devices. The aiming was proposed to be carried out using a system consisting of a set of levers, rods and sectors on which a mechanical sight was placed. When changing the position of the barrel, the sight moved in the vertical plane as required, indicating the point of splashdown of the projectile.
The 190-mm anti-submarine howitzer was supposed to use special shells. First, ammunition was developed based on the design of a standard high-explosive grenade for 7.5-inch howitzers. It had a metal body with an ogival head, weighed 100 pounds (45.4 kg) and carried a charge of 43 pounds (19.5 kg) TNT. A contact fuse with a two-second delay was used, which was triggered after hitting the water or breaking through the hull of the target submarine. To launch the projectile, a powder charge of a relatively low mass was used.
Later, a heavier and more powerful anti-submarine ammunition was created. It featured a different hull shape and weighed 500 pounds (227 kg). Half the mass of such a projectile was explosive. A separate propellant charge for this shot was not developed.
Depending on the elevation angle, the BL 7.5-inch naval howitzer could attack targets at different ranges. When using the earlier "light" projectile, the initial speed was only 146 m / s, and the maximum firing range reached 2100 yards (1920 m). 500-pound ammunition could be sent at a distance of no more than 300 yards (275 m). A direct hit from both shells could cause fatal damage to the submarine. Medium or minor damage was possible with a miss of up to several tens of meters, but the submarine's incapacitation was no longer guaranteed.
The crew of the cruiser HMS Vindictive and a 7.5-inch howitzer. The photo was taken after the ship returned from the Zeebrugge raid in April 1918.
The development of the BL 7.5-inch naval howitzer project, followed by the assembly and testing of prototypes, continued until the end of the spring of 1917. After receiving positive reviews, the gun was recommended for mass production. In June of the same year, the industry handed over to the fleet the first batch of howitzers. In total, it was planned to make several batches of such weapons - a total of at least one thousand units.
According to reports, the serial production of 190-mm howitzers continued at least until mid-1918. By December 1917, the customer received just under 400 systems. The rest were delivered later. During the entire production period, Great Britain produced 950 guns in the original configuration. After that, an updated howitzer was put into production. Unlike the basic product, the new gun had a smooth barrel. In addition, there were some other minor improvements.
After the completion of the release of the guns, improved shells were developed. The only difference between such ammunition was the presence of a special ring on the warhead. This made it possible to shoot at low elevation angles, without fear of ricochets from the water and confidently hitting underwater targets.
Record production rates have made it possible to equip a significant number of ships and vessels of the military and merchant navy with the BL 7.5-inch naval howitzer systems. The main carriers of such weapons were light and medium patrol boats and ships. In addition, a significant part of howitzers were intended for transports, which were the main target of enemy submarines. A significant number of anti-submarine howitzers were installed on large ships of various types. For example, the cruiser HMS Vindictive received a couple of such systems.
It should be noted that not all the positive features of the new weapon were successfully implemented in practice. The absence of recoil devices made special demands on the strength of the deck and imposed restrictions on the placement of the howitzer. In addition, circular guidance has always been impossible due to the presence of superstructures, gun turrets, etc. Nevertheless, even with such restrictions, ships and vessels received a certain chance to fight submarines.
German submarines posed a great danger to the British fleet, and therefore anti-submarine systems were of particular importance. Nevertheless, for various reasons, very little is known about the operation of the BL 7.5-inch naval howitzer. Moreover, almost all of the surviving information describes the use of this weapon for other purposes. However, even these cases are of certain interest.
On March 28, 1918, a 190 mm howitzer was used in combat with a submarine, but the submarine was not its target. It all started when the crew of one of the transport ships noticed an approaching torpedo. The ammunition was 600 yards away (less than 550 m) and was heading towards the ship. Having made the correct lead, the gunners were able to lay the 7, 5-inch round next to the torpedo. From the explosion, she changed course and rose to the surface of the water at a distance of about 60 yards from the vessel. The second well-aimed shot and the subsequent explosion immobilized the torpedo. The escort ship soon found and examined the torpedo: it was seriously damaged and lost its charging compartment.
Australian transport howitzer SS Orca, 6 March 1919
On April 23, 1918, the Royal Navy's naval group conducted the so-called. Raid on Zeebrugge. The fleet of 75 ships and boats included several carriers of 190 mm howitzers, including the cruiser HMS Vindictive. The risk of attack by submarines was minimal, so they decided to use anti-submarine weapons as conventional artillery. The crews of the BL 7.5-inch naval howitzer were supposed to attack the indicated coastal objects, enemy ships and vessels, etc. At the same time, the main task of the guns of the cruiser HMS Vindictive was to support the actions of the marines landed on the coast.
Information on other cases of combat use of howitzers BL 7.5-inch naval howitzer is missing. It can be assumed that such a weapon should have shown an acceptable probability of hitting targets. The advantages of such a system include the possibility of free aiming at different angles (with known limitations), as well as a relatively high rate of fire. The relatively small mass of the explosive charge, the low muzzle velocity and the long duration of the projectile's flight, in turn, were disadvantages.
However, it is not difficult to determine that a "light" projectile, when fired at maximum range, could remain in the air for up to 20-25 seconds. When firing at a moving target, such a flight time could be critical, but not in all cases the enemy's submarine had a chance to go to a safe distance. In addition, the calculation of the gun could take into account similar shooting features when preparing for a shot. A direct hit on the target or a small miss in the same way could compensate for the relatively small mass of an explosive charge in a "light" projectile.
An analysis of the experience of testing and operating 190-mm anti-submarine howitzers showed that such a weapon has good performance and is of interest to the fleet. Already in 1917-18, several new projects of this kind were launched. Their goal was to create completely new systems or adapt existing weapons for new tasks. In the course of the further development of existing ideas, the caliber of the anti-submarine howitzer was gradually brought to 13.5 inches (343 mm), and some of these samples even entered service.
Serial BL 7.5-inch naval howitzer, which the fleet had in large numbers, remained in service until a certain time. In the future, carriers of such weapons began to be written off and sent for scrap. The howitzers followed them. By the mid-twenties, the Royal Navy of Great Britain completely abandoned such weapons. As far as we know, not a single 190-mm naval howitzer has survived to this day.
The negative experience of interaction with German submarines demonstrated the importance of creating new anti-submarine systems. On the basis of already known and original ideas, promising projects of one kind or another were soon created. Soon, some of the samples entered service. As for the idea of an anti-submarine artillery gun, it reached practical use, and then interested foreign naval forces. Soon, a similar sample of naval weapons was created by American designers.
