There more to Uniforms than just protection. One looks at the progression of Armor, from the Bronze Age Helmets and Shield, to the Iron Age of the Greek and Roman, to the full suited Knights of the 12th and 13th. Century., and, protection is the first thing to come to mind. But there more.
It Protection, and Utility, but it also tradition, it Inspiration, and Intimidation, and it Pride.
Things which may appear silly to those who do not know, like the Epaulets on Uniforms continuing up thru W.W.I, but these do serve, beside there obvious function of itentfing rank, a useful function. They help to protect the Shoulder bone from the glancing blow of a Saber from horse back.
The BiCorn hat, worn side ways for captains and fore and aft for Litinuts has it origins in the Roman head gear, where the Centurion would have the Comb on his helmet, the Side to Side for the Command of the whole column, and the Fore and aft for each unit. It being the Whole column could se the Centurions Comb, and each of his officers under him, there combs, so that the whole knew where they where heading, Simple communications.
The TriCorn Hat, a staple of 17th. And 18th,. Century fashion, gets it start in the Military. If one wearing a broad brim hat, and then try handling a Pike, the brim of the hat gets in the way, same with doing Drill and loading with the new Muskets, so one side of the hat gets pined back,. (Thank of the Slouch hat with the Feather in it of the Caviler during the English Civil War) Next step was to pin both left and right flaps, and pinning the rear became natural.
I always said, the first weapon of European Army's was to try and Intimidate your opponents army by letting see how well dressed yours Army is.
An another example, the Famous Polished Winged Hussars of the 14th thru the 17th. Century, those wings where not just to show, but there where whistles which screamed as the Hussars road at full gallop at you, those wings fluttering and making the rider look larger, more terrifying. The Solderers who where on the receiving end of the Winged Hussars, where half beaten before the first blow, with fear as they saw the Hussars charging, and there mighty reputations.
Any way, that a start.