Given that animals use camouflage as a natural part of both their defence and offence strategies, it is amazing how little credence the Great War combatant nations gave to its employment on the early battlefields. To be sure the British, after the disasters in South Africa, when the Boer crack-riflemen picked off the red-coated infantry with depressing accuracy, had long adopted their khaki (Urdu/Persian = dusty) battle-dress. The Germans had followed with the adoption of feldgrau (green-grey), as had the Russians with their grey-brown uniforms. However, the French, at least initially, stubbornly stuck to their bright red trousers, blue frock-coats and kepis. Their cuirassiers even rode into battle with highly burnished breast-plates: seldom in warfare can there have been more opportunistic targets than those that these shining breast-plated warriors presented to the German jagers and machine-gunners. It is debatable whether the sky blue uniforms, that eventually became the French standard battle-dress, were actually a really optimal and effective replacement.
Nevertheless, it was the French who, in 1915, first introduced sections de camouflage on the Western Front spurred on by the realisation that aerial warfare made camouflage an essential element in the prosecution of the land war. Professional artists were asked to suggest how judiciously applied colour could be used to break up the shape of military objects so as to confuse and confound both the aerial observers (in aircraft and balloons), and those in the opposing enemy trenches. The need was particularly important with the introduction of large artillery pieces and, after 1916, the highly visible, and mobile, tank.
A strong influence on the French camouflageurs was the work of the Cubist Movement who used the slow graduation from light to dark colours to break up and flatten out the shape of an object. Picasso's cubist paintings, such as 'A seated Woman', painted in 1910, is an excellent example and, indeed, it could be taken as a fair representation of a modern female soldier in camouflage combat dress.
In the Great War
However, the first observations on the use of protective colour graduations in animals, and their possible application in warfare, were made in the late 19th Century by an American (Abbott Thayer) and a Briton (John Kerr). Along with Solomon J. Solomon, and others, both these zoologists became involved with what was perhaps the most prominent camouflage exercise of the Great War- the 'dazzle-painting' of both war-ships and merchant vessels. Basically, the whole of the ship above the water-line was painted with angular patterns, or curved lines, in primary colours. The principle was to break-up the silhouette of the ship to give the enemy (e.g. U-Boat captain) a false perspective which would make it more difficult to judge the distance, course and speed of the intended target. To allow for the necessary deflection of a torpedo, or gun-fire, a U-Boat captain, or ship's gunner, needed to estimate the course, speed and distance of the target with some precision. The dazzle painting was intended to make this more difficult by a collective illusion. Over the course of the war over 4,000 merchant ships and naval escorts were so painted. Whether this had a really significant effect is a moot point. But modern warships do not use dazzle painting; modern technology would not be so easily deceived.
The more general use of camouflage on the battle-field met with great success and, by the end of the Great War, had become standard practice in all arms of the land-forces. However, anecdotal reports indicate it was not always readily accepted without equivocation by some die-hard officers. One such was a French brass-hat who decreed that false tree-trunks fabricated for front-line observers should not exceed a certain diameter so as to be aesthetically 'correct'. Once inside the trunk the more substantial bodied observers could not get out again and the trees had to be removed by rescuers for them to be extricated. Much to the hilarity and, no doubt, considerable sport of the enemy.
It is said that some modern soldiers do not feel they are real soldiers unless they are wearing camouflage uniforms and most armies now have their own particular camouflage pattern.