A facing colour is a common tailoring technique for European military uniforms where the visible inside lining of a standard military jacket, coat or tunic is of a different colour to that of the garment itself. The jacket lining evolved to be of different coloured material, then of specific hues. Accordingly when the material was turned back on itself: the cuffs, lapels and tails of the jacket exposed the contrasting colours of the lining or facings, enabling ready visual distinction of different units: regiments, divisions or battalions each with their own specific and prominent colours. While a popular practice in 18th century armies, the use of facings was especially observed and elaborated on during the Napoleonic Wars.
During the Ancien Régime, there were many different facing colours (notably various shades of blue, red, yellow, green and black) on the standard grey-white uniforms of the French line infantry. Examples included blue for the Régiment du Languedoc, red for the Régiment du Béarn etc. The initiative in fixing or changing facing colours was largely left to individual colonels, who in effect had ownership of their regiments. This tendency towards variegated facings reached its height in the "Dress Regulation Facings for the Army" of 31 May 1776 when unusual shades such as silver-grey, aurore and "red speckled with white" were added to the by-then white uniforms of the French infantry. In 1791 an attempt was made to rationalize facings by giving groupings of up to six regiments a single colour, relying on secondary features such as piping or button patterns to distinguish separate units.
The rise of mass conscript armies during and following the Napoleonic Wars led to increasing standardisation of facing colours, for reasons both of economy and supply efficiency. Thus, for example, the French line fusiliers and grenadiers of the early 19th century had red facings, with only numbers to distinguish one regiment from another. The voltigeurs had yellow or/and green facings. From 1854 on red facings became universal for all of the line infantry who made up the bulk of the French metropolitan Army, although the Chasseurs, who constituted a separate branch, retained yellow facings as a special distinction.