Complex sentence: The Abwehr was now monitored round the clock and the volume and regularity of the material obtained enabled Bletchley to achieve one of its great triumphs in December 1941, when the Abwehr's Enigma cypher, giving enormous insight into German intelligence operations.
Split into simpler sentences: The Abwehr was now monitored round the clock and the volume and regularity of the material obtained enabled Bletchley to achieve one of its great triumphs. In December 1941, the Enigma cypher of the Abwehr was broken, giving enormous insight into German intelligence operations.