Was reading a book on Alexander the Great the other day. Alexander is legendary for his tactical and strategic superiority on the field of battle and one of the methods he employed was this.
Alexander realised that in order to successfully coordinate large groups of troops in the field, it would be necessary to communicate timing to his battalions and so he instructed his Alchemists to develop dyes that would change colour when exposed to air. Rags would be dipped in these dyes and sealed in air tight containers. Alexander would distribute these containers to his commanders and upon exposure to air, they would change colour, thus signifying the time for that battalion to attack. As dyes were formulated to change colour at differing times, Alexander could coordinate timing amongst his various battalions with these rags.
They were widely known as Alexander's rag time-bands.
Sorry! Sorry! Sorry!
Actually not as a gay man Alexander was into colours and feathers etc he often had his clothes dyed the same way so that they would change colour with the weather.
psst! I think he's having you on. 
