In 1795 a tax was imposed on hair powder, which led to its rapidly beginning to go out of fashion, so that twenty years later it was only to be found on the heads of rich men's servants, as a sign of conspicuous consumption. (Strange that governments still think that they can make something go better by making it more expensive). So the army's edict was roughly in tune with the fashion of the times, and since officers were supposed to be very 'smart', their abandoning the practice probably sped up the coming of the fashion. At the same time, Romantic and neo-classical tendencies led to a desire for a freer, more natural hairstyle, which was what developed in place of the queue.

Cheers

C