Uniforms during the Napoleonic period were made from woollen cloth. "White" wool is naturally grey and needs to be bleached to turn it into true white - this was done by treating wool with stale urine and leaving it in the sun for several months. Fabric dyes during the period were all derived from natural sources, synthetic dyes not being developed until the second half of the 19th century^(1). The most important property for a dye for army uniform use was fastness - that is resistance to fading or running due to exposure to sun and weather. There was only a few dyes (the so-called great dyes) that were fast enough for military use in their uniforms:

· Madder - A Eurasian plant which produced a brownish-red maroon colour

· Cochineal - Made from powdered tropical insects native to America and produced a truer scarlet colour compared to madder.^(2)

· Indigo - Produced from a tropical plant native to India and South-East Asia but most production was in the Americas by the 17th century, producing dark blue dye. Woad is a Eurasian plant that produced a similar colour to Indigo but with a much smaller yield.

· Weld - A Eurasian plant that produced a yellow dye. This was still not entirely fast and needed to treated with alum salts and cream of tartar to fix the colour.^(3)

· Old Fustic and Quercitron - American plants that produced yellow dye at a much greater yield than weld. Old fustic produced a duller, more brown yellow. Querctiron dye had only been discovered in 1771.

· Walnut Husks - Produced brown dye, primarily from the English/Persian Walnut tree

Other colours could be produced by mixing these dyes - greens by dying a cloth first yellow and then overdying with blue (or vice-versa to produce slightly different shades) and grey could be produced by using exhausted blue dye. Oranges could be produced by using an alkali mordant with madder dye and purples could be created by mixing madder and indigo^(4). Black was very difficult to achieve - it required numerous dye baths to produce a dark colour and was thus very expensive and usually faded quickly to an unpleasant green colour, true blacks requiring synthetic dyes.

The small number of usable dyes meant that there was a restricted palette of colours available for military use - grey, white, red, blue, green and brown. Yellow dyes were troublesome; consistent shades were hard to attain and yellows were prone to fading.^(5) Yellow or buff was once a relatively common uniform colour but had died away in the 18th century, the Neufchatel battalion being the only major infantry unit during the Napoleonic period to use it. The Prussian 2nd Cuirassiers wore a buff tunic until 1808 and several Prussian Hussar regiments had used yellow until the post-Jena reforms. Some Swedish cavalry units from Scania had eye-catching yellow uniforms. Orange and purple were generally seen as unmilitary shades; however they were commonly used as facing colours and for musicians.

European powers had settled on national colours for their armies beginning from the 1670's^(6) and here the most important consideration seems to be have been cost rather than any symbolic importance. France and Austria, the two powers with largest armies, unsurprisingly chose the cheapest option of unbleached grey wool; however both switched to bleached white wool during the first half of the 18th century due to its superior appearance. Britain chose red as it had access to cheap madder dyed cloth, red having being used Parliamentarian armies during the Civil War; while the Russian choice of Green seems to have been based on Peter the Great's personal preference. There were major Woad production centres in Northern Germany - the regions of Julich and Thuringia - and as a result many German armies used blue coats - Prussia, Bavaria, Wurttemburg (after the 1750's, white prior to that), Hesse and Baden. Hannover, the Hanseatic cities and Denmark used red, likely due to access to cheap Dutch madder grown in Brabant; Saxony originally wore red but had changed to white coats after their army was reorganised in 1734. Spain and Portugal had access to cheap Indigo from the Americas and so used blue uniforms; they were also large producers of Walnut and as such used brown cloth extensively as well.^(7)

While financial considerations may have been at the forefront in the initial decision on colours, uniform colours did acquire symbolic significance through the 18th and 19th centuries. Cromwell's New Model Army had worn red coats and the image of the red coat became synonymous with the English soldier. Bavarian blue coats were of lighter coloured cornflower blue rather than the usual dark blue reflecting the traditional Wittelsbach dynastic colours; similarly Swedish uniforms were traditionally blue with yellow facings. Saxony may have given up their red uniforms in 1734, but the Grenadier Guard regiment retained its red coats well into the 19th century. Sometimes symbolic importance was invented after the fact - the Duke of Brunswick had raised a corps while in exile in Bohemia in 1809, wearing black uniforms ostensibly in mourning for the previous Duke who had been killed at Jena in 1806; in reality the black uniforms likely came from the plentiful supplies of civilian black cloth. Regardless, black uniforms became a defining feature of Brunswick's uniforms until the adoption of grey uniforms at the end of the century. France had equipped their infantry with red trousers from 1829 in an effort to support the local madder growing industry and they quickly became so linked to the image of the French soldier that synthetic red dye was need to be imported from Germany after the collapse of the French madder industry. Attempts by the army to adopt modern low visibility uniforms were met with shouts of "Red trousers are France" from politicians; it was only after the bloody days of 1914 that the uniform colour was changed to low visibility blue-grey (bleu horizon).

The French use of indigo blue uniforms demonstrates how uniforms could gain symbolic importance in a short period of time. The pre-revolution French infantry had used white coats, however the prestigious Régiment des Gardes Françaises had worn a dark blue uniform with red facings and white lace. The French Guards had been very sympathetic to the Revolution and were at the forefront of the storming of the Bastille. They were disbanded in August 1789, but formed the core of the Paris National Guard, bringing their old uniform colours with them. Most National Guard units across France then copied the uniform with its newly patriotic tricolore colour scheme.^(8) THe name of the dark blue colour was changed from Royal Blue to National Blue.^(9) The new National Guard units and the old Royal Army units (still in their white coats) had been placed into combined units and when a new uniform was being chosen the dark blue of the National Guard was retained. Napoleon faced with the British blockade; spiralling army costs and having decided to stop indigo imports as part of the Continental System instituted a large scale experiment in 1806 trialling the renewed use of white uniforms. The experiment was not a success - the uniforms looked terrible after slogging through the Polish mid during the 1807 campaign, blood from wounds showed up easily to the detriment of morale and the troops were reluctant to give up their tricolore uniforms. Napoleon attempted to stimulate the local woad industry - Languedoc had been a major centre of woad cultivation during the 18th century - but results were disappointing despite Napoleon sponsoring a 500,000 franc prize for anyone able to increase the yield of Woad.^(10) The Emperor was eventually forced to re-open trade in Indigo, though prices rose steadily due to difficulties in shipping supplies from the Western Hemisphere. The Bourbons had tried to reinstitute white uniforms after Waterloo in an effort to rebuild a more compliant army, however the idea was catastrophically unpopular - white coats were now indelibly associated with the Austrians - and was abandoned in 1820 when blue uniforms faced red were reintroduced. Intentionally or not, the tricolore effect was retained with white buttons and cross straps.