TheCodeBreakers
code of about 45,000 five-digit groups, enciphered by two volumes of
50,000 five-digit additives each. The b, or second, edition had come into
force on December 1, 1940, and by the following November messages in
it were partly readable. At 6 a.m. on December 4, 1941, new additive
books came into effect, together with new indicators. Fabian's group
broke into this new encipherment four days later, and by Christmas
messages were again being read as before. But these readings were
tantalizingly fragmentary, and much remained to be done.
The commencement of hostilities generated an enormous increase in
radio traffic and consequently in the workload of the Combat Intelligence
Unit. To handle it, the unit dragooned personnel from every possible
source. It first acquired the band of the U.S.S. California, which had been
badly damaged in the first few minutes of the air attack. Dyer threw up
his hands when he heard about it, but music and mathematics and
annaabi.ee 
