I can't really see any advantage to having cumbersome uniforms with a lot of decorations and seemingly useless accessories, so why did uniforms of the past seem ornate as opposed to comfortable and functional?
Functionality was often a secondary concern in the look of full dress uniforms, say, prior to the 1840s.^1 This is a subject well conveyed in Scott Myerly's British Military Spectacle, one of the few scholarly works I'm familiar with which examines in detail the topic of military uniforms.^2 While I take some objection to a few of his claims, for the most part I find his argument convincing- Namely that the military show in general, and the costume and appearance of soldiers in particular, was essential to both the allure of the military profession (for individuals of both high and low status), and the coercive effect of military force in Industrial England.
Nevertheless, it should be noted that Myerly, and indeed most military historians discussing the height of British military splendour and impracticality during the period between 1815-1854, have full-dress uniforms in mind. Full dress, as the name implies, was only worn in specific instances. Whilst not entirely ceremonial, the wearing of full-dress was restricted to special occasions, particularly during the early 19th century era of ostentation.
What was worn in its stead? The uniforms specially adapted for overseas theaters may have been worn as far back as the the late 17th century. Watercolors produced by Wenesclas Hollar of the British Garrison at Tangier during the reign of Charles II show officers in grey uniforms with small hats. We can identify definite trends towards campaign adaptation of impractical uniforms in the following century. During the 18th century, full dress was adapted to colonial theaters. Here, I will be using England as an example. In North America during the 7 Years War, British troops cut down the long skirts of their coats, and trimmed their caps in order to adapt their dress to the rugged and inhospitable terrain encountered in the colonies. Later, during the American Revolution, British soldiers substituted their coats and breeches (now, it should be noted, of a different and more elegant pattern to those worn in the previous conflict) for jackets and gaiter-trousers (made to cover the whole of the leg, and attach at the instep of the shoe). Similar dress, accompanied by a fur-crested round-hat, was the 'Indian uniform' worn by soldiers serving in the subcontinent during the late 18th century.
The practice of colonial adaptations developed and expanded through the 19th century. Again, using Britain as an example, practically all the military conflicts which British soldiers fought were colonial campaigns. The dress worn on these campaigns were as diverse as the environments in which they were fought. However, in the first half of the 19th century was ibvariably improvised and based from existing, and impractical, models worn at home. Take India, for example. In the winter months, troops wore the undress uniform worn in England- though often with the addition of trousers made locally of nankeen or dungaree and covering their caps in white cloth. In the summer, troops wore locally made jackets and trousers of white-drill cloth. These adaptations were made with the discretion of the commanding officer, and some regiments (the 24th in the Second Sikh War, for example), persisted in wearing their uncomfortable full-dress.
Elsewhere in the British Empire, soldiers adhered less strictly to dress regulations. For example, soldiers in South Africa stripped the lace from their coats and substituted their caps or shakos for stocking-caps or wide-awake hats. Footwear was made locally, and equipment carried 'en bandarole', i.e., worn wrapped in a blanket slung over the right shoulder.
Which brings us to the only European campaign fought by the British Army in the 19th century, the Crimean War. The traditional narrative of the Crimean war shows the British Army as moribund from the 'long peace', totally unprepared for the circumstances of an actual war, and hopelessly inept when fighting it. While not entirely incorrect, this narrative does not tell the whole story. The subject of military uniforms in the Crimea is often brought up as time and again as a telling visual representation for the conservative and unreformed army. In many aspects, their costumes appeared to differ but little from those worn at Waterloo four decades earlier.^3 The Crimea was a war with another European power (Russia) and so would be a full-dress affair. Indeed, the uniforms worn by British troops were highly unsuitable to the conditions they experienced whilst campaigning in the peninsula. Again, however, it would be a mistake to assume British troops fought in 'skin-tight breeches' or other highly impractical garb, entirely oblivious to the needs of modern warfare- As some contemporaries alleged, and a myth which many historians have been content to repeat. The photographs by Fenton often show officers to have worn rather loose-fitting coatees (the tail-coat worn in full-dress). Both officers and men accommodated to conditions on campaign- notably taking the first opportunity to discard their shakos. Later, the weather suffered by British troops completely destroyed any semblance of full-dress elegance in the Army of the East.
So- I feel I've rambled on for way too long, and I'm still not sure if I've fully answered your question. I've chosen to end with the mid 19th century, as then the trend in military fashion, which had already been moving away from elegance, tends towards practicality (with no odd periods of outlandish ostentation, as was seen in England during the reign of George IV) finally culminating in the near-universal adoption of service dress by European Armies at the turn of the 20th century. Please feel free to ask any more questions you might have, or if you need any points clarified.
Sources:
Barthorp, Michael. The British Army on Campaign 1816-1902 (1-4) (Osprey, 1987-88)
British Infantry Uniforms since 1660 (Blandford, 1982)
Carman, W.Y. British Military Uniforms from Contemporary Pictures: Henry VII to the Present Day (Arco, 1968)
Mollo, John. Military Fashion (Putnam, 1972)
Uniforms of the American Revolution (Blandford, 1975)
Myerly, Scott Hughes. British Military Spectacle: From the Napoleonic Wars to the Crimea (Harvard, 1996)
Schick, Ingrid T. Battledress: The Uniforms of the World's Great Armies 1700 to the Present (Artus, 1993)
^1 During the the 1840's, the French, Prussian, and Austrian armies all adopted the tunic, which replaced the earlier tail-coat as standard wear for soldiers. Britain adopted the tunic somewhat later.
^2 Gah, me and footnotes today- Anyway, military uniforms are a sadly neglected topic for scholarly research. Uniforms can be as informative to the field of military history, as say, the subject of historical costume can be to social history. (A line I've paraphrased hap-hazardly from Thomas Ablers' Hinterland Warriors and Military Dress)
^3 At risk of seeming even more pedantic, this is also an erroneous assertion. Whilst the basic component of jacket (or coatee, as the long-skirted tailcoat worn by troops in the Crimea was known) and trousers remained the same from the Napoleonic wars, numerous modifications occured. These were often Victorian-era simplifications of regency excesses in military fashion.
Im assuming you are talking about the Napoleonic era wars where the British are portrayed as wearing bright red uniforms. The reason they did this was to be seen/identified on the battlefield since the battles had changed from swords to guns. The guns of the Napoleonic era didnt use gunpowder as we understand it now but rather it used a powder that produced a large amount of smoke.
With several thousand weapons firing at the same time over a long period of time it became much more difficult to identify who is friend or foe. So the brightly coloured uniforms were merely a way to identify who was friend or foe easily.
This changed for the British during the Boer war however when they went up against the Boers who decimated the British attackers who were extremely easy to see at long range due to their bright red uniforms. The reason being was that the Boers were excellent marksmen and used rudimentary camouflage to hide themselves from the British troops. After this they transitioned to the Khaki uniforms you see in Indiana Jones.
There also needs to be a distinction drawn between what you wore when you got your picture taken (or portrait painted) and what you wore when you actually went into battle. Ceremonial uniforms can be pretty ridiculous but they're for wearing to look good, not fight in.
Many details of modern uniforms are actually symbolic of some aspect of the uniform that was originally there for function. For instance the quatrefoil (or knot) on top of the hats that US Marines wear was, originally, used so that sharpshooters in the rigging of ships didn't fire on their own marines during boarding. Marine hats still have the knot embroidered onto the top of the hat for this reason.
hi - there are a couple of military-related posts in this section of the FAQ - check it out for more responses
Smokeless powder was invented in the mid-19th century; prior to this invention they had a real problem: heavy smoke made it really difficult to make out who you are shooting at. so the danger or friendly fire would be very real. A colorful red uniform made it easier to identify friend from foe.
