After hostilities commenced in August 1914 the Admiralty's secret intelligence unit, Room 40, stepped- up its monitoring and codebreaking operations against Germany; providing the British armed forces with' tide-turning information about the enemy's plans. This second of a two-part series highlights Room 40's operations from the outbreak of hostilities to the' war's end. ROOM 40 WAS the Admiralty's secret intelligence-gathering and -processing department that provided vital intelligence to the British military commands and their allies during the First World War. Based in the Admiralty Building in London, it was in several ways a predecessor to the more concerted and sophisticated code-breaking operations at Bletchley Park during the Second World War. Part one of this look at Room 40's contribution to the war effort (ET, June 2014) surveyed the role played by Admiralty intelligence in the lead-up to the declaration of hostilities in August 1914. Soon after this it became clear to all national combatants that the ability to adjust and change to meet new circumstances would define the winners and the losers. The British had already moved to protect its globally-encompassing telegraph cable network - the 'All-Red Line' - and had curtailed German international telegraph communications by cutting five subsea German cables off the Atlantic coast. At the start of the war, codes and ciphers deployed by the military, naval, and diplomatic services on all sides were relatively primitive, derived from the age of the cavalry on land and of sail at sea. There was an awareness of the need for secrecy, so signals were first encoded using common codebooks; then, for additional security, signals were enciphered. The concepts underlying these techniques, however, were distinctly old-fashioned, and also increasingly vulnerable to innovations in code-breaking techniques.
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