I was just casually thinking about the Roman Empire (as one usually does).

It was 15th of March yesterday, the ides of March day. It was the day Julius Caesar was assassinated by Senators of Roman Republic.

Suddenly I remembered that Caesar had reformed the calendar in his time, and I started thinking – how does one go about doing that?

So I did what any sane person does. I opened Wikipedia.

Before Caesar introduced a new calendar, the Romans used a lunar calendar, which counted months based on lunar cycles (much like the Hindu calendar). It had 355 days in a year.

This meant that Romans were falling behind on time, and had to add a leap month periodically to keep the calendar in sync with the solar year.

By year 46 BC, the calendar was full 3 months out of sync with the solar calendar because these leap months were missed in confusion caused by civil war between Caesar and Pompey.

Caesar, now the dictator of Rome, decided to fix this mess, and move to a solar calendar called the Julian Calendar.

To make sure the dates were correct, year 46 BC had a leap month (after February) and 2 extra months (before December). In total, there were 445 days in 46 BC. Year 46 BC is nicknamed the annus confusionis (“year of confusion”) and is the longest recorded calendar year in human history!

The new year began on 1st January 45 BC, as per the Julian Calendar.

A great reminder of how so many things that we know, and take for granted, are just made up things, all in our head!

Fun Fact: Caesar was assassinated the very next year, 44 BC, presumably by senators who also had to code DateTime parsing libraries on the side.