Sestertius - Trajan S P Q R OPTIMO PRINCIPI S C

The inscription OPTIMO PRINCIPI — "to the best ruler" — was not a generic honorific. The Senate formally voted Trajan that title in 114 AD, though it appears on coinage somewhat earlier, reflecting the gradual consolidation of a reputation built through the Dacian campaigns and an unusually cooperative relationship between emperor and Senate. No previous emperor had received it officially.

RIC II 579 falls within the period bracketing the first and second Dacian Wars, the latter concluding with Decebalus's suicide in 106 AD.