Military uniform
While certain distinctive features emerged - such as the red pompon worn on the crown of the French sailor's cap, the open fronted jacket of the German Navy or the white round cap of the U.S. Navy - the overall pattern remained standard until the development of specialist working or protective rigs during the Second World War.

American Civil War: It is generally supposed that Union soldiers wore blue uniforms and Confederate soldiers wore grey ones.  However, this was only a generalisation.  Both the Union and the Confederacy drew up uniform regulations, but as a matter of practical reality neither side was able to fully equip its men at the outbreak of the war. Existing state units and quickly raised volunteer regiments on both sides wore a wide variety of styles and colours in the early stages of the war.  Some regiments—such as the North's Berdan Sharpshooters and the South's Alexandria Rifles—had green uniforms, while the French zouave style was widely imitated.
The Union eventually got most of its men into regulation Federal blue but this often faded until it appeared grey. Originally the Confederate government relied on the "commutation" system which required the states to provide their own uniforms. While the commutation system was in place, many states were not able to provide an ample supply of uniforms and captured federal uniforms were common. Later in the war the Confederate national government provided uniforms from a central depot system, including the famous Richmond and Columbus depots. Many photographs of Confederate soldiers from later in the war (usually casualties) are wearing standardised uniforms. As Sherman's men marched across Georgia and up the Carolinas, they were cut off from supply by the Union and began wearing clothing of Confederate origin. Confederate soldiers used a variety of vegetable and imported dyes which would fade to a "butternut" colour.

End of bright colours: Until 1914 the majority of armies still provided colourful dress uniforms for all ranks, at least for parade and off-duty wear. These often retained distinctive features from the past. Most Russian troops, for example, wore the very dark green introduced by Peter the Great in 1700. German infantry generally wore the dark "Prussian blue" of the previous two centuries. This and other features of the historic Prussian Army uniform were generally adopted by the other German States as they fell under Prussian influence before and after the Franco-Prussian War of 1870. Bavarians, however, continued to wear light blue and Saxon regiments retained a number of distinctions after the establishment of the German Empire (1871). Two regiments of the Prussian Guard and one of the Russian were still issued with the brass mitre caps of the 18th-century grenadier. The British infantry retained their scarlet tunics for parade and "walking out" wear, while the bulk of French regiments wore red trousers with dark or light blue tunics. The infantry of the Austro-Hungarian Empire discarded their historic white tunics in 1868 in favour of dark blue. However, the extremely large number of colours appearing on collars, cuffs, and shoulder straps to distinguish the various regiments were retained. There were for example ten shades of red, ranging from cherry red to pink. The Swedish Army had favoured dark blue with yellow facings since the beginning of the 18th century. There was infinite variety, even within smaller armies, between regiments, branches or ranks and the subject is a complex one.

The British were the first to introduce drab/khaki uniforms: in 1848 in India. This khaki drill then became more generally worn from the Indian Rebellion of 1857 both in India and Africa. A darker version, known as "service drab", was adopted for home service field wear in 1902, the same year that the US Army also adopted khaki for non-dress occasions. The Italians introduced grey-green in 1909, followed by the German and Austrian armies who adopted different shades of grey. The Russians had changed to a grey shade of khaki in 1908, following their experience in the Russo-Japanese War of 1905. There was however strong attachment to the colourful uniforms as previously worn on all occasions and the process was not an inexorable one. The Danish Army adopted grey-green uniforms for all occasions in 1903, reverted to a combination of dark and light blue in 1910, took up light grey in 1915 and finally settled for khaki in 1923. The Imperial Russian armies, following their adoption of khaki-grey field uniforms in 1908, took the opportunity to upgrade their parade uniforms to much more elaborate and colorful styles, and were experimenting with a mix of khaki and bright colours when war broke out in 1914. The Japanese Army probably went further than most in adopting khaki for all occasions after 1905, although even here officers of all branches and the cavalry of the Imperial Guard retained traditional coloured uniforms for formal and ceremonial occasions.
With the exception of Western-influenced units such as the "Ever-Triumphant Army" of the Taiping Rebellion (1851–66), Chinese armies of the 19th century wore dress that was broadly variegated. Embroidered chest panels and coloured buttons on headdresses were used to distinguish rank and sometimes unit. From 1910 the Imperial Chinese Army adopted dark blue uniforms of Japanese style with coloured facings of red, white, or yellow to distinguish the different branches. The Imperial Guard Division had a light grey uniform with the same branch colours as the line. A khaki summer uniform was worn by the entire army.

By the 20th century, drab colours were increasingly being adopted for active service and ordinary duty wear. The First World War finally put an end to the expensive practice of furnishing colourful uniforms to all ranks of the various armies. Amongst the frontline troops in August 1914 only the Belgian and French armies saw active service in bright colours and old fashioned headgear (although the Austro-Hungarian cavalry retained their blue and red uniforms for field wear after the remainder of the army had gone into pike grey in 1909). The Imperial German field grey of 1910 retained a number of traditional features such as spiked helmets, shakos, busbies, and coloured piping from the older uniforms. The demands of modern warfare as well as financial economy soon saw these survivals vanish, and by 1916 all involved armies were in either khaki (Russia, Turkish, Serbia, Montenegro, Japan, Greek, French colonial, and Britain), various shades of grey (German, Italian, Bulgarian, Portuguese, and Austro-Hungarian) or sky blue (French and Romanian). The coloured uniforms of peacetime were often relegated to depot wear by recruits doing their basic training.
Steel helmets first appeared in the form of the "Adrian" helmet adopted by the French Army in 1915. The practical advantages of this innovation led the British and German armies to adopt their own helmets by 1916. Other armies followed suit – the Belgians and Italians for example copying the French model and the Austro-Hungarians that of Germany.

Interwar period: The drab uniforms of 1914–18 remained in general use until the Second World War. This was partly for political reasons, since the republican, fascist, Nazis, and communist regimes that replaced many of the old monarchies and empires had little interest in preserving the splendours of their predecessors. However, even in those societies where there was social and political continuity the trend was away from the traditional uniforms worn prior to 1914. The British Army reintroduced full dress for Guards regiments in 1919-20 and regimental bands by 1928, while permitting officers to wear their mess (evening), blue or green "patrols" (semi-formal) and full dress on appropriate occasions. The French reintroduced "grande tenue" in 1927 for North African regiments which were mostly dependent on voluntary recruiting, and after 1930 required all regular officers to acquire dress uniforms in the pre-1914 colours of their branch or regiment. Elsewhere full or coloured dress of traditional cut was generally restricted to formal uniforms for officers and long service regulars, ceremonial guards, and a few other limited categories. The Spanish Army (which had not been involved in the First World War) exceptionally continued to issue coloured uniforms to all its conscript rank and file until 1926 and thereafter to the garrisons of Seville, Barcelona, and Madrid for special ceremonials until 1931. These included red trousers for the line infantry, following the French practice in an example of cross-border influence.
The use of steel helmets was by now almost universal and a number of countries adopted their own designs moving away from the German, British, and French models of the First World War. The Italians, Soviets, Japanese, Swiss, Spanish and Portuguese were amongst these. Steel helmets, originally simply items of utilitarian protective clothing, were adopted as parade headdress by the French, German, Italian, and Soviet armies, amongst others, between the Wars.

Second World War: Uniforms of varying shades of khaki and grey were universal in the Second World War but the cut and outline appearance of the different armies still made identification in the field relatively straight forward. A Soviet soldier would, for example be distinguishable from his German opponent by his general outline, even in the fog of battle. British, American, Japanese and French uniforms still retained some distinctive features, even as they became more and more utilitarian in the course of the War.