Intelligence from The Companion to British Hi...

Intelligence, i.e. information on rivals, has always depended mainly on public or semi-public sources such as the accounts of travellers and ships' captains, the use of reference works and directories, the compilation of statistics and latterly aerial and space photography and directional wireless. The political and martial intentions of states can often be inferred from the jigsaw puzzle of such variegated facts so long as there is a centre where that puzzle is put together. Under primitive conditions much depended, too, on the relative speed with which information, often of an ordinary kind, could be transmitted. Secret intelligence (i.e. the penetration to matter which is being deliberately concealed) and counter-intelligence (the protection against hostile intelligence operations and sometimes their deception) were first practised in some detail by the Venetians. The English, reputedly very skilled, seem to have undertaken them spasmodically. Under Elizabeth I, Walsingham and Burghley were well informed through Sir Thomas Gresham of confidential political and financial matters in the Spanish Netherlands and they also frustrated several conspiracies and brought Mary Queen of Scots to the block. In the War of the Spanish Succession Marlborough, mainly through Cadogan, organised a very effective network which even had an agent (identity unknown) of high standing at the French court. Daniel Defoe is also thought to have been concerned in counterintelligence. In the French wars of 1793 to 1815 the British, mainly through the Foreign Office and the Admiralty, were very well informed on the state of Europe because the oppressed peoples were glad to supply or transmit information. It is said that the secret terms of the Treaty of Tilsit were known in London before they had reached Paris. It was at this period that the regular censorship of ordinary mail (as opposed to the clandestine opening of diplomatic mail) became an important feature of intelligence practice. It was to dominate other sources in World War I. See Cipher; M.I.

The Companion to British History, Routledge