This photograph was taken either at Kilworth, Co. Cork, or in Aldershot. After completing their training, Fred Bailey of Stourton (2nd from left, front row) and his fellow Hampshire Regiment “Pioneers” went over to France in December 1915. For a contemporary semaphore training film sequence click here.

As semaphore depended on a line of sight and was readily neutralised by enemy action, its efficacy was limited. An almost insurmountable difficulty was the need to hide the meaning of messages from enemy observers by the use of codes.

This entailed the existence of code books, which had to be continually replaced, with all the confusion and need for organisation that might entail. In the continual to-and-froing of trench warfare, it was almost impossible to ensure security of the codes for a practical period of time without their falling into the hands of the enemy, or doubts arising whether they had done so.

Semaphore was much more successful at sea - it is said that Admiral Lord Nelson’s sailors employed a vocabulary of 70,000 signals using only 18 flags.

The chart below is from a publication of 1918.