D.D. Communications

On Friday 12th May 1916, Signaller Sydney Fuller, 8th Suffolk, wrote in his diary;
"Practiced sending "D.D." messages with "discs". A DD message was one which was not answered or acknowledged by the receiving station. Each word was repeated once - thus a message reading, for instance "short of bombs" would, if sent by the DD method, read "short short of of bombs bombs""
In an age where communications were in the form of bugle, flag and runner, the need to send important messages quickly and securely was paramount. The DD system which required an un-acknowledging receiving station, was the safest way of getting a message through. The enemy were almost certain in an attack to concentrate on the lines of communication and flag signals which could be both read and acknowledged, could also be seen by the enemy, who could then call down artillery on the receiving station once they had identified its position. The DD system could be observed from receivers in concealed positions who need not reveal themselves to the enemy. In the battles that was to come, carefully concealed tree houses were effective receiving stations, from where the message could be sent onwards by telephone.
Fuller continued; "The discs were intended for use for such messages sent from advanced positions only. They consisted of a disc of tin or sheet iron about a foot in diameter, on a light pole about four feet long. The back of the disc, which would be towards the enemy when in use, was "camouflage" painted, and the front was white, with a black diagonal bar. they were used in the same way as flags."

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