CENSORSHIP SECRETS. DETECTION OF SPIES. CUNNING ENEMY DEVICES.
Many and fascinating will be the stories told in future years of the activities of the various Government departments to combat the cunning methods by which Germany waged war during the past four and a half years, and not the least interesting will be that which recounts the work of the British postal censorship. From small beginnings it grew to large proportions, dealing with more than 130 languages and dialects, and with the most crafty devices on the part of the enemy either to smuggle much-needed commodities into Germany or to obtain valuable secret information.
The ingenuity displayed in deciphering codes, in discovering invisible writing, in obliterating all trace of its chemical treatment of suspected letters, and, above all, in preventing the undue dislocation of trade, must always stand to the credit of one of the most efficient departments created by the war. Invisible writing may be done in saliva, milk, lemon juice, or in various chemical solutions. Each is revealed by its own peculiar treatment, yet a chemical solution has been discovered in the censorship laboratory which succeeds in revealing practically every one of these forms. On August 3, 1914, the day before war was declared against Germany, an officer was instructed to take up the duties of the Postal Censorship. During the following days a few officers and volunteers assisted in opening the mails for Germany, and a staff of civilian censors began to be assembled. At the end of December 1914, the staff numbered 170, and was housed in the General Post Office. By the end of October 1918, it had increased to 4,680, of whom 1,093 were men and 3,587 were women. The bulk of this staff was housed in Strand House, and occupied six floors and the basement of that large building. Of the remainder 173 men and 1,256 women worked in the censorship at Liverpool, where the mails between the United Kingdom and North and South America are handled.
Each examiner read on an average 110 private letters or 86 commercial letters a day. The average number of letters censored in a day was 375,517, weighing about four tons. Of these 116,700 were commercial letters and 258,817 were private letters. In the censorship of private letters and parcels women have been found specially useful, as they have a wonderful memory for detail, and can recognise again peculiarities in handwriting, form, and expression which they have once remarked.
Little by little every channel of communications by mail between neutral European countries and other neutral countries outside Europe was also brought under supervision, while for transit mails passing between more distant localities a network of censorships was established at convenient points throughout the Empire.