45 BC

By place

Roman Republic

• Consuls: Gaius Julius Caesar, without colleague.
• January 1 - The Julian calendar takes effect as the civil calendar of the Roman Empire, establishing a solar calendar that is, at the time, identical to the Egyptian calendar.
• March 17 - Civil War: In his last victory, Julius Caesar defeats the Pompeian forces of Titus Labienus and Pompey the younger in the Battle of Munda. Labienus dies in battle, Pompey the younger is executed, but Sextus Pompey escapes to take command of the remnants of the Pompeian fleet.
• The veterans of Julius Caesar's Legions Legio XIII Gemina and Legio X Equestris demobilize. The veterans of the 10th legion are settled in Narbo, while those of the 13th are given somewhat better lands in Italia itself.
• Caesar is named dictator for life.
• Caesar probably writes his Commentaries in this year.

  Asia

• Possible first year of the Azes I Era.