although the second frederick of sicily, he chose to call himself "frederick iii" (being one of the rare medieval monarchs who actually used a regnal number) – presumably because only some fifty years before, his well-known and remembered great-grandfather had reigned sicily and also used an official ordinal: "fridericus secundus, imperator etc.". thus, "fridericus tertius" was better in line with the precedent of his ancestor's ordinal. however, an anecdote attributes frederick's choice of numeral to him being the third son of peter. the next man called frederick to occupy the sicilian throne was dubbed by later generations of historians as frederick iii: frederick iii the simple, though he himself did not use an ordinal.