Signal for victory: the development of naval communication technology in Plymouth command

With Britain currently in a stage of lockdown, communication with each other has gained added importance. Whether it is video calling our family or emailing work, the use of communication technology has become essential in the running of day to day life. Although the scale of the lockdown is something that has been rarely seen in British history, the use of new communication strategies is not a recent development. Drawing on the early stages of my PHD research, this blog post will highlight how the evolution of technology helped to establish Plymouth as a significant naval communications centre in the Second World War.

Throughout its history, Plymouth has been significantly defined by its location. With access to the Channel and the Atlantic, the port prospered during the Elizabethan era with sailors, such as Drake and Hawkins, making their name. In 1690 the Royal Navy decided to construct Devonport Dockyard. With the port firmly established as a key fleet repair facility, the naval presence in Plymouth was placed under the command of a Port Admiral. Usually the most naval senior officer in Plymouth at the time, the Admiral was responsible for the co-ordination of naval operations, such as the protection of coastal convoys. This was done from his flagship. To alleviate these cramped conditions, construction started on a new land-based headquarters at Mount Wise in 1808. Situated near the newly built Government House, Admiralty House was well positioned.

At the start of the nineteenth century the Royal Navy began to experiment with new forms of communication. A key innovation was the development of the shutter telegraph system. Originally pioneered by the Frenchman Claude Chappel, the use of shutter telegraphy was adopted by the Admiralty in 1795 to communicate with different naval bases. Although a line of communication was created to bases such as Sheerness and Portsmouth by 1796, it was ten years before Plymouth was connected to the network. Built in 1806 within the Mount Wise redoubt, the shutter system allowed Plymouth to send and receive messages at speed. In July 1806, Inspector of Telegraphs, George Roebuck, reported that he had received a reply from Plymouth after sending a message from London in just twenty minutes. In total, there were twenty-eight signal stations between Admiralty Headquarters in London and Mount Wise in Plymouth; the penultimate one being on the heights at Saltram House. 

Echoing the days of the Armada, where lookouts were stationed across the country at fire beacons ready to pass on news of a potential Spanish invasion, signal stations were manned by a four person team. Housed in a small wooden shack, this comprised of a Royal Navy lieutenant, a midshipman, and two assistants.

Each member of this team had specific duties, ranging from working the shutters to reporting the signals. As part of a cost cutting initiative following the defeat of Napoleon, the shutter station was closed in September 1814, and it would not be until 1852 before Plymouth would be reconnected to London. Despite this however, a semaphore station was built on the site of the old Shutter telegraph and appears to have been in use as late as 1914. A local visitor guide notes:

‘Crowning Mount Wise is a little fort and semaphore signal station, whence orders are signalled to the warships in the Hamoaze and in Plymouth Sound… Wireless telegraphy, the telephone, and the telegraph have not by any means entirely rendered the method of signalling by semaphores obsolete. Every day the apparatus at Mount Wise is in frequent use…’.

This mix of old and new technology is difficult to explain, however one reason could simply be ease of use. The transition to new communication technology had not gone so smoothly in the past. One of the earliest regular messages sent by the Admiralty to Plymouth was the daily time signal marking one o’clock. The introduction of electric telegraphy in 1852 caused confusion with this signal with Plymouth still being on local time, around seventeen minutes behind London. That being said, Plymouth played an important part in the development of wireless telegraphy. In the late nineteenth century Plymouth was the location of the torpedo school HMS Defiance. Although primarily a torpedo training facility, Defiance also served as a school for electrical engineering. It was here that her commanding officer, Henry Jackson, tested out one of the first primitive radio sets by sending messages to Admiralty House at Mount Wise. Through corresponding closely with Guglielmo Marconi, the renown Italian inventor, Jackson and the Defiance electrical school, helped to develop a radio set which was robust enough to withstand life at sea. As a result, wireless was adopted permanently by the Royal Navy from 1901 onwards. The use of wireless was not restricted to naval vessels however.

By the start of the Second World War Royal Navy establishments, such as Plymouth Command, relied extensively on wireless communication to carry out their duties, such as convoy defence. In November 1939 the Commander in Chief at Plymouth, or Western Approaches at it was known, Sir Martin Dunbar-Nasmith highlighted the need to provide better protection for the ‘W/T, teleprinter and telephone systems’ feeding into his headquarters as they were ‘most vulnerable to attack’. The importance of maintaining these lines of communication can be shown in the lead up to D Day. In 1944 Plymouth was one of the key build up sites for landing craft and other naval vessels in the invasion of Europe. Supervising this massive logistical operation was the Plymouth Command War Bunker, known as Area Combined Headquarters (A.C.H.Q). Still visible in the Gardens of Admiralty House at Mount Wise to this day, the A.C.H.Q acted as an important intelligence and communication hub. In the weeks and months prior to D Day, representatives of the Royal Navy, Army and RAF worked in close corporation to co-ordinate operations. To do this a large team of cyphers, coders and typists, mainly women, worked tirelessly to process and communicate vital information.