The Adventures of Prince Achmed, 1926. Source: Wikipedia
With tools such as DRM and copy protection, the movie industry is waging an apparently losing battle against film pirates. How long has this fight been going on?
At least since the 1890s:
Film tinting: "The process [of tinting film] began in the 1890s, originally as a copy-guard against film pirates. The film was tinted amber, the color of the safelight on film printers. The discovery of bleaching methods by pirates soon put an end to this."