Signal Intelligence: The Luftwaffe, under the Red code, began using a new, previously unused reflector. It was called the Unkehrwalze Dora (UKD) by the Germans, and it posed a potentially devastating problem for the British at Bletchley Park. Fortunately for the British, the Germans adopted the measure gradually and very slowly. It should be noted that the British had already adopted a similar measure on their Typex code, as early as November 1941.
