Well - no, it is just a historical date.
Yes, today is March 15th, and if you are referring to Cesar's death - it was bad for him, and it marked the transition from the Roman Republic into the Roman Empire; Julius Cesar had, perhaps, much merit as an author of Latin prose and as a conqueror for Rome's and especially his own glory, but he was also a tyrant, like many other dictators, monarchs, generals and leaders.
https://en.wikipedia.org/wiki/Et_tu,_Brute%3F
("Et tu, Brute?", in Italian and French versions: "Tu quoque, mi fili?").
https://en.wikipedia.org/wiki/Julius_Caesar
https://en.wikipedia.org/wiki/Alea_iacta_est
https://en.wikipedia.org/wiki/Rubicon
His successor, Gaius Octavius Augustus, after having eliminated the Second Triumvirate, became Rome's first emperor, or Rome's "Princeps Civitatis" (First Citizen) ...
https://en.wikipedia.org/wiki/Pax_Romana
And, not to forget:
https://en.wikipedia.org/wiki/Jesus