At first glance Dazzle seems unlikely camouflage, drawing attention to the ship rather than hiding it, but this technique was developed after the Allied Navies were unable to develop effective means to disguise ships in all weather.
Dazzle did not conceal the ship but made it difficult for the enemy to estimate its type, size, speed and heading. The idea was to disrupt the visual rangefinders used for naval artillery. Its purpose was confusion rather than concealment. An observer would find it difficult to know exactly whether the stern or the bow is in view; and it would be equally difficult to estimate whether the observed vessel is moving towards or away from the observer's position.
In the UK, the British Army introduced its Camouflage Section at the end of 1916; while at sea, the marine painter Norman Wilkinson invented the concept of dazzle painting as a way of using stripes and disrupted lines to confuse the enemy about the speed and dimensions of a ship. Wilkinson, then a lieutenant commander on Royal Navy patrol duty, implemented the precursor of "dazzle" on SS Industry; and HMS Alsatian became the first Navy ship in August 1917.
All British patterns were different, first tested on small wooden models viewed through a periscope in a studio. Most of the model designs were painted by women from London's Royal Academy of Arts. A foreman then scaled up their designs for the real thing. Painters, however, were not alone in the project. Creative people including sculptors, abstract artists, and set designers designed camouflage.
Dazzle's effectiveness is not certain. The British Admiralty concluded it had no effect on submarine attacks, but boosted crew morale. It also increased the morale of people not involved in fighting; hundreds of wonderfully coloured ships in dock was nothing ever seen before or since.
In a 1919 lecture, Norman Wilkinson explained:
The primary object of this scheme was not so much to cause the enemy to miss his shot when actually in firing position, but to mislead him, when the ship was first sighted, as to the correct position to take up. [Dazzle was a] method to produce an effect by paint in such a way that all accepted forms of a ship are broken up by masses of strongly contrasted colour, consequently making it a matter of difficulty for a submarine to decide on the exact course of the vessel to be attacked.... The colours mostly in use were black, white, blue and green.... When making a design for a vessel, vertical lines were largely avoided. Sloping lines, curves and stripes are by far the best and give greater distortion.
During both World Wars, former ocean liners owned by British steamship companies like Cunard Line were re-commissioned as an integral part of the British fleet. These auxiliary vessels were re-fitted with armament and re-painted in the same manner as other fleet ships. For example, the Canadian Pacific Steamships RMS Empress of Russia and White Star Line RMS Olympic (sister ship of the ill-fated RMS Titanic), former passenger liners, were given the "dazzle" treatment when used as troopships.