This is the Italian epic of Julius Caesar from 1914. Much like Cabiria in length and scope and also in expressing the imperial ambitions of Italy at the time (even though the fascists hadn't yet come to power). Apparently this, the international version, was toned down while the Italian version was more agressive. Dutch intertitles - but the story of Caesar is of course well known (or easy to learn quickly from wikipedia). Historical article: "Caesar, Cinema, and National Identity in the 1910s" in: Julius Caesar in Western Culture, Maria Wyke ed., (2006).