During the First World War, British and Americans began to look at various visual deception paint schemes as ways of protecting their boats. The most striking one, which certainly appeared to work in tests, was known as Dazzle camouflage. It made it difficult for a U-boat commander looking through a periscope to judge exactly what angle the ship was travelling at. After the war, basically everyone gave up on camouflage paint schemes because it wasn't relevant since ships were now mainly being detected via radar, sonar and other means.