the fort of othona is in a typical late 3rd century style, and was possibly constructed during or shortly prior to the carausian revolt, making it contemporary with the forts at dubris, portus lemanis and gariannonum. according to the early 5th-century "notitia dignitatum", which is the only contemporary document mentioning othona, the fort was garrisoned by a "numerus fortensium" (""numerus" of the brave ones").