I think I remember something in a Tom Robbins book about the time some French military officials asked Picasso to suggest a camouflage scheme for their soldiers. His answer: "Dress them as harlequins." I guess he was onto something. (After a search, I found this page with another version of the story).
Here's a wonderful article about the history of "dazzle camouflage" written by Roy R. Behrens. (I also really like the design of Behren's site. It's simple and beautiful.)
The most familiar kinds of camouflage make one thing appear to be two, two things one, and so on. Camouflage artists (called camoufleurs) make it an arduous challenge to see a figure on a ground (called blending), or to distinguish one category of object from another (mimicry). Less familiar but potentially far more effective is disruptive or dazzle camouflage in which a single thing appears to be a hodgepodge of unrelated components.
The purpose of dazzle painting a ship was not to make it invisible (indeed, at times the dazzle pattern made it more visible), but simply to divert the aim of the submarine gunner, who was required to "aim ahead" of a distant, moving target, under less than ideal viewing conditions, and who thus depended on critically accurate estimates of the ship's speed, direction and location.