Why shell-dye spotting emerged across navies

Who first implemented dye in naval shells, and when?

Several major navies converged on the idea during the 1920s, making priority claims difficult to resolve.

Several major navies developed shell-dye spotting during the 1920s while reviewing lessons from Jutland. Priority is contested because claims about inventing the method differ from claims about first using it. Independent development is considered plausible because the idea followed readily from a shared gunnery problem. No single navy receives an uncontested claim to the invention.