The Development of Fire Control Systems on Warships
Prepared by Sargon (hopefully with future additions from other members of The Battleship Brothers)
Up to the last years of the 19th Century (1890s), gunfire was done more or less in the traditional manner with each gun crew firing when the sights came 'on' during the roll of a ship and all gun crews acting independently in this regard. Of course, orders were sent from the bridge in a variety of ways from flags, bugle calls, and speaking tubes to sheer shouting. However, an officer in the RN realised this was affecting accuracy with the larger and larger guns that were being introduced, and wished to do something to address peacetime training where gunners would engage in leisurely target practice against moored targets on clear days with calm waters, with hit averages of 20 to 30 percent. This officer was called Captain Percy Scott, and he knew that these percentages would fall to abysmal levels in real battle conditions, especially with the greater ranges engagements were expected to be fought at.
He introduced a variety of devices to address this issue. First of all, he wished to develop the idea of continuous aiming and compensate for rolling, so that a target could be kept on sight using rapid gun elevation and depression. He introduced a device called the 'dotter' to solve this issue. Next, to improve the training of guns onto a target he introduced the 'deflection teacher', which helped in compensating for a target's movement. He also introduced a 'loader' to improve rates of fire. In another important move he encouraged a spirit of extreme competition between gun crews of different vessels in order to become the best shooting ships in the fleet. This had impressive results, raising hit percentages to around 80 percent.
At the same time, in the US, Rear Admiral Bradley Fiske introduced a telescopic sight, which improved firing accuracy by narrowing a gunner's field of view. He ultimately managed to introduce range finders into the US by around 1900. He appreciated the value of heights, so he mounted range indicators high up in masts, developing the technique known as 'aloft spotting' which allowed a more accurate picture of what was happening in an action to be noted. This proved its worth at the Battle of Manila in 1898.
Scott also introduced telescopic sights into the RN and also saw the advantage of directing fire from heights, and came up with the idea of 'director firing' which centralised gunnery control to a single position high up in the ship, thus allowing all gun crews to receive the same information by different methods such as signalling, speaking tube, and later on by internal telephone and electronic relay.
RN Admiral Jackie Fisher was a proponent of long range gunnery, and his drive and influence led to an number of innovations such as the 'Dumaresq calculator' which read off changes in the heading and range of a target, predicting the fall of shot for salvoes more accurately. Next up was the coincidence range-finder which further refined this concept. Later on a combined range finder with plotting table was created by Arthur Follen which added further refinement defining the relative movement of a target by calculating the movement, speed and position of BOTH the target and the ship it was plotting from. It displayed this information on a piece of paper in a continuous fashion.
The Battle of Tsushima in 1905 showed that large numbers of different sizes and calibres of guns made spotting harder, so intermediate batteries were abandoned, with the trend being towards large main guns and much smaller light guns. Sometimes, even these light guns were reduced to just large enough to prove a threat to torpedo boats. An example of this are the first dreadnoughts which didn't even have a real secondary armament. This also led to changes in gun arrangements and the introduction of superfiring turrets, meaning a ship could carry fewer turrets, thus saving weight which could be used for other attributes and also improving arcs of fire. This was initially hampered by blast effects going through the sighting hoods on top of turrets, but the US addressed this by moving such hoods to the sides of turrets, and the first battleships in the world to use these were the USS South Carolina and Michigan. Wing turrets persisted in most European navies for a while though before being abandoned.
By 1912, improvements in gunnery had become even more advanced. HMS Thunderer was equipped with direction equipment and took part in a competition with her sister HMS Orion which did not. Thunderer achieved 13 hits and 10 near-misses using 39 shells, whilst Orion could only manage a paltry 2 hits and 2 near-misses for 27 rounds. This was decisive in convincing the Admiralty to equip every capital ship in the fleet with director gear by 1913. Fire control tables were also being developed that cross-checked observations to cancel out more errors. In Germany, longer bases were introduced to rangefinders to cope with increases in distances that guns could fire at - this was very useful in that gunners didn't have to wait for shell splashes to appear before opening fire. Triple turrets were introduced in Italy in their Dante Alighieri Class of battleships, but these were not favoured by the RN or the HSF because they did not work well with the established controlled salvo alternate gun per turret firing doctrine. However, this didn't put off the Austrians who adopted triples in their Viribus Unitis Class of dreadnoughts.
Following World War I, lessons were learnt and the concept of the armoured director mounted high in the ship was introduced. The RN adopted 'ladder firing', which had previously been used by the HSF, where salvoes were fired together according to a group of ranges calculated by the range finder. This had the advantage of speeding up shooting, since one did not need to wait to see the results of the previous salvo before firing the next. Range clocks were often fitted in fighting tops to relay ranges to other ships in the battleline, and training lines painted on turrets to show what position they were aimed at.
As ranges increased, it became necessary to increase the elevation of guns, and this posed loading problems, which were addressed by 'all angle' loading or machinery that sped up the elevation and depression of guns so that they could be returned to level, loaded and elevated back up very rapidly to resume firing.
Effects of the roll of the ship were further cancelled out by the US introduction of the 'stable element', which computed the ship's roll and used a gyroscope to keep the guns at a fixed angle relative to the horizon even in very heavy swells.
Spotter aircraft were also embarked to be launched during battle to pinpoint fall of shot over the horizon. There is some evidence that the Japanese battleship Yamato's spotter craft *may* have enabled her to achieve a straddle or even hits on a target at the Battle of Samar during the Leyte Gulf campaign in late 1944 at a distance of around 39-40,000 yards. However, to date the only confirmed longest range hit records on moving targets without the aid of aircraft are held by HMS Warspite when firing on the Italian fleet at Calabria, and the German battlecruiser Scharnhorst when firing on HMS Glorious. Both were around 26,000 yards.
Optics for rangefinding as well as stereoscopic rangefinders were further developed reaching a peak with the best optical equipment ever put to sea. The Germans had very good optical rangefinders which allowed them to obtain hits early on in battle, but the system was very labour intensive and put a lot of strain on the director crew, so accuracy would fall off after a while. The Japanese for their part undoubtedly shipped the best optics in the world with the final word in the form of huge triple 50 foot optical rangefinders being carried on the massive Yamato class, the largest battleships ever built. In both cases, crews needed to be specially trained to use them, and only those with the best eyesight were chosen. Like the Germans, it could be a strain on the operatives to work the equipment for extended periods of time and fatigue would reduce accuracy after a while. Such directors also usually required more crew to operate than standard ones. However with radar guided fire control and ranging, it became far easier to improve accuracy, less of a strain, and less labour intensive.
It was also common for each main turret to possess its own range finding gear to enable local firing in case the main and secondary positions were both knocked out. Yamato for example carried rangefinders just as large as those in her fighting tops in her turrets. Due to the fact that these devices were mounted much lower on a ship, accuracy was not as good or effective as the rangefinders carried higher up, plus the overall gunnery of the ship would suffer if using these due the lack of central direction.
Centralised director control for secondary guns was also introduced interwar, making these weapons more effective in combat, and casemates were rapidly abandoned in favour of small turrets or gun-shields, providing better all-weather operational capability than the often water-logged and restricted firing arc casemates.
During the late 1920s and throughout the 1930s into the 1940s, as aircraft became perceived as more of a potential threat, anti-aircraft artillery was also added, and central control for these developed apace right up to the radar control that was used so effectively by the US Navy in Word War II. It goes without saying that radar had a huge effect upon main and secondary gunnery, enabling true over-the-horizon blind-firing in all weathers as its ultimate development, the magnificent US Iowa class being prime examples of a good battleship design shipping this type of equipment.