It's worth noting that the reason the calends had slipped so badly is because it was Julius Caesar's job as pontifex maximus to handle the periodic updates to the calends that kept it in sync with the solar year. But he was too busy fighting in Gaul and having his adventures to bother with it for years, so the calendar slipped into chaos due to his mismanagement. He then went on to fix his screw-up, but he didn't just decide to fix the calendar, he was in a position where he'd screwed up so long he had to fix it.
Caesar procrastinated so hard he changed time itself!
(This is funny, but I'd be interested to read a source on how true this is. Presumably there were priests that could take care of such things. He took care of lots of other Roman business while he was in Gaul.)
Can't beat Canadian Prime Minister and Founding Father John MacDonald blacking out while drunk during the Fenian Raids (Irish American civil war vets fighting for Irish freedom by attempting to invade British North America as a bargaining chip) in the 1860s [0]
And Julius Cesar in fact outsourced his duties! He hired some priests from Egypt to fix the calendar. And it didn't work right away, because the Egyptians told the Romans to add an extra day in the fourth year, but the Romans counted inclusively so they thought it was every three years.
