As I left my office last week, in which I work on a Monday as an unpaid volunteer, I nearly tripped over a couple of BID660 and BID580 machines {still with their plug fields and card readers} and a box containing half a dozen SP02628 Callsign encryption and decryption devices that we used to call "fruit machines". I am amazed to see the size of the BID machines when they are not locked into their customary 19-inch racks.  Of course, many years ago all this now junk was TOP SECRET, whose job it was to change highly sensitive plain language into a cipher which literally, nobody ever cracked. I spent many years of my life using this type of equipment, and when I came across the book I talk about below, its contents were almost second nature to me. I found it fascinating, and I am sure that those of you out there with a comparable background to that of my own, will at least find this short page interesting. I hope so.

Communicating by

was of course universally used by all literate people of Nelson's time, although in the mid to late 18th century and early 19th century not all had yet mastered the art.  For those who had, exchanging written correspondence was a laboured event indeed, with long waits before an answer was received. No airmail; no first class post [rather like today in 2005] and a stage coach, which conveyed the letters, likely to be intercepted by highwaymen often resulting in the mail being lost.    
Nelson was brought up in a period where other forms of communicating were the norm, when flags, sound signals, and the guard-boat [in harbour] made or conveyed signals around the gathered fleet. Outside this gathered group of ships, sending and receiving signals was painfully slow often taking a couple of weeks to get an answer, and admirals had to despatch small sloops or frigates [called pickets] from their group to act as messengers. On land, messages were passed from the Admiralty by semaphore involving many semaphore towers each within sight of one another. This was regularly used from London to Chatham and to Portsmouth. You may occasionally see a church flying a white ensign {most fly the flag of St George}, and this is allowed because once upon a time, that church, probably because it was the tallest building in the area, had a semaphore tower on top of it and was part of the Defence Communications System of the 18th and 19th centuries.
Also by Nelson's time, codes, albeit in their infancy, had been formulated and were used mainly for military purpose. However, they were codes employed for speed [brevity] rather than for security and were rarely seen or intercepted by the enemy. On the other hand [pardon the pun] hand written letters regularly used a secret code just in case they were intercepted.  Today, still considering brevity and speed, much of what is in the International Code of Signals [INTCO], used by all sea farers and which transcends all languages and national custom/rules/regulations, comes from the time of the Napoleonic Wars and the early 19th century.  It therefore started with naval sayings, doings, manoeuvres and the like, and picked-up mercantile terms as it grew in size to its present volume.
Land armies therefore had an advantage over naval fleets, by using semaphore signals over long ranges, heliograph signals, fast horses in relays, hot-air balloons, spies, fifth columnists etc to extend their communications, but for Nelson and his captains, the crows-nest was as good as it got. Moreover, for the next 80 or so years, naval fleet communications were stuck in a time warp, whilst  army communications had a head start.
  The British army also used it with success and of course it revolutionised land communications overnight.  At sea, the navy couldn't use it [cables and wires not long enough!] and their only salvation was the signalling lantern made available by the introduction of electricity. At least the signalling lantern could dramatically increase the range over which visual communications were possible, so a step in the right direction.  The navy missed out again when the telephone was invented, it too being a land tool, which armies used to supplement the telegraph, the semaphore towers, their heliographs etc etc. When first invented [do you remember the cowboy films of those days when the telegraph was always involved in some plot or other and the baddies shinned up posts in the outback to cut the wires?] and used for civilian purposes, it was expensive because each word, or even letter, was charged for separately. Thus people [except the Marshal of course] used it sparingly. Bit by bit the system was improved, but come the start of the American Civil War, it was still very expensive to civilians. Very soon after the first shots were fired both the Damn Yankees and the Johnnie Reb's set-up their own military telegraph, and they used code words and occasionally, encryption.  This increased the speed of transmission, but slowed things down for the coder and the decoder ends. By 1865, after four years of dreadful all out war, military communicators were au fait with codes and encryption and could assemble and disassemble telegraph stations wherever required either for an advance or for a retreat. Soldiers had become able communicator's. At the time of Queen Victoria's Ruby Jubilee in 1877, several attempts had been made to standardise and internationalise a telegraph code, so that a message leaving say, London, could be fully understood in say,  Durban and all points south which handled the message. By this time, the INTCO [see above] was in full and daily use at sea, and telegraph systems were now world wide even in undeveloped areas of the world.  Places like Great Britain already had codes of their own run by the General Post Office and then the BBC, and they were jealously guarded: anything but international. A man called Causon-Thue had publish a book containing codes which he called the ABC of Telegraphic Codes in the 1870's, but in 1879, there was an international conference on the subject, which led Causon-Thue to issue the fourth edition of his ABC. This edition, he proudly states, is specially adapted for the use of Financiers, Merchants, Shipping Owners, Brokers, Agents etc and guarantees SIMPLICITY [everybody can understand it], ECONOMY [fewer letters and words are required] SECRECY [the encryption of the code is easy and virtually impossible to break by code-breakers]. What follows is a very quick look at an example of his codes taken from the ABC Telegraphic Code of 1883. Click to enlarge First, I want you to imagine a book which has no fewer than 25,400 sentences or groups of words and each one is given a unique number called a CODE NUMBER and a CODE WORD. Here is an example of just a couple of pages of the book . When a suitable sentence does not already exist, users can invent them by choosing their own 5 figure numbers and code word. Click to enlarge

  Using the page example above, let us imagine that the message to be sent is all about Wrens going to sea for the first time, and the crew, all males as yet, have been at sea for six months.  From the pages our message will be "10th September" [from page 260] "For the good of the Service" [from page 261] "keep them separate" [from page 260] "it is very serious" [from page 261]. Using the ABC, the message to transmit is simply the CODE WORDS for the four sentences viz "SIGILADO SIMILARITY SICCATIVE SILLABUS" and that is it.  Alternatively one could have transmitted the CODE NUMBERS, when the message would have been "12981 13014 12959 13004" which might have been neater and better anyway. Clearly all CODE NUMBERS must have five figures and that is all well and good for sentences 10000 to 25400 and beyond. For sentence number 1 to 9999, noughts have to added to bring the number up to five figures.  Thus sentence 1 becomes 00001 and sentence 9999 becomes 09999. Now lets assume that the admirals wanted this message concealed from the fleet at large, after all, everybody has a copy of this ABC Book. We need some crypto, and as yet, one-time-pad and seascout have not been thought of. Mr Clauson-Thue has printed in his book the following cipher table. His way is simplicity itself. He writes down two rows of data, one above the other. In the top row he fills each space with the numbers 1 to 0, and in the bottom row, ten different letters [no repeats].  In this example I have used the word CUMBERLAND which gives a matrix of:-
1 2 3 4 5 6 7 8 9 0
C U M B E R L A N D

To encode this message, we use the CODE NUMBERS, and not the CODE NAME. Take the first CODE NUMBER namely 12981 from the example above. Looking at the two lines of data above, a '1' becomes a 'C', a '2' becomes a 'U' etc., until the code for 12891 becomes 'CUANC'. The rest of the message is ' CMDCB CUNEN CMDDB'. This message will afford better than good security in a limited period, and was no less sophisticated in its time than naval ciphers. However, I did spy a couple of potential weaknesses. Click to enlarge

In these pages he has produced many variables each again of ten separate letters, and you can see that the pattern has endless possibilities, which can change hourly, daily [like our old keycards] or as a one-off for a specific message.
Every port in the world has been assigned a code word and a code number. Some of the naval ports are listed as:-
 
Hong Kong LABIADAS 21319
Singapore LOGISTICA 21653
Aden HACENDUELA 21159
Malta LAPPAGINIS 21459
Gibraltar HUMECTAVIT 21354
Bermuda HERETESCO 21208
Plymouth LEVADOURA 21553
Portsmouth LIBERRIMO 21565
Chatham HISOPEABA 21276
Portland LIBONOTUS 21567
Penarth LEPRETTINO 21540
Edinburgh HORRENTES 21321
Alexandria HACQUETON 21162
Halifax N.S. HURONEABAS 21371

Just using four of these ports in cipher, it would be possible, with the following 10-letter settings chosen at random, to produce names that might be all telling!

MALTA {21459} with a setting of O M P S T E G U A H would result in MOSTA
PENARTH - I was once stationed there on the Algerine sweeper HMS HARE, with A W H E L X Y Z J S = WALES
GIBRALTAR {21354}, with setting O M L S E K J G P H produces MOLES
HONG KONG {21319} with A T M S L K P F R X produces, of all words, TAMAR.

Well that is it folks. By 1888 Marconi and Captain Jackson Royal Navy were playing with radio, and very soon, side by side, we had 'wireless systems' and 'wire and cable systems', which is still extant to this very day. HMS Hector, which was sold for breaking up in 1905, was the first to be fitted with wireless telegraphy.   Wireless system released the navy from its time warp and for the first time, it could 'flex-its-wings' and compete fairly with army communicators. Although still in its embryonic stages, radio had a somewhat limited operational role in the Boer war fought at the turn of the century, and by the time of WW1 in 1914, it was well established and a going concern.