In which year was dazzle camouflage first used?

The picture shows HMS "Tamar," one of the UK’s Royal Navy patrol craft, in 2021. Its colour scheme is a modern example of dazzle camouflage, developed in the early 20th century.

Camouflage is usually thought of as an attempt to conceal by using colours and textures that blend in with a background. So, at first glance, dazzle seems an unlikely form of camouflage, drawing attention to the ship rather than hiding it. The approach was developed after Allied navies in World War 1 were unable to develop effective means to hide ships in all weather conditions. In 1917, heavy losses of merchant ships to Germany's unrestricted submarine warfare campaign led to a desire for new methods of camouflage.

The intention of dazzle camouflage is not to conceal but to make it difficult to estimate a target's range, speed, and heading. The marine painter Norman Wilkinson promoted a system of stripes and broken lines to distort the external shape by violent colour contrasts and confuse the enemy about the speed and dimensions of a ship. Over 4000 British merchant ships were painted in dazzle camouflage; dazzle was also applied to some 400 Royal Navy vessels, starting in August 1917. Dazzle was also adopted by the United States Navy in 1918.

Technological improvements in range-finding eventually made dazzle less effective.