The paper brings the activities of the French administration during the Illyrian provinces, in Dalmatia, namely Split and its surroundings from 1812 to 1814. The 16,120 preserved documents, books and legal acts reveal the functions, competences and fields of activity of the government’s Royal sub-delegation in Split. The administrative organization of the sub-delegate’s bureau and administration was reconstructed following the original registered system of the central French administration on the lower administrative level. Extended administrative, judicial, educational, economic, military, social and cultural activities in Split and its surroundings give an insight into all peculiarities of the then short-lived French rule and administration on the level of district. The Archives of the Royal sub-delegation in Split is one of the most important historic sources for studying events in Dalmatia in the time of the Illyrian provinces.