43 BC

By place

Roman Republic

• Consuls: Gaius Vibius Pansa Caetronianus and Aulus Hirtius. The Roman Senate confirms Octavian as propraetor with joint responsibility for the campaign against Antony. Hirtius and Octavian mobilize troops for the march to Mutina, while Pansa continues the levy. Embassy dispatched to treat with Antony.
• Gaius Antonius is defeated by Marcus Junius Brutus at Dyrrachium. Brutus proceeds to secure his position in Thrace and Macedonia. Gaius Cassius Longinus campaigns in Syria and defeats the army of Publius Cornelius Dolabella at Laodicea.
• March – Vibius Pansa set out to link up with Hirtius and Octavian, bringing four legions of recruits, having left one, the legio urbana, to defend Rome.
• April 14 – Battle of Forum Gallorum: Mark Antony, besieging Caesar's assassin Decimus Brutus in Mutina, defeats the forces of the consul Pansa, but is then immediately defeated by the army of the other consul, Hirtius. Both consuls are killed.
• April 21
• * Cicero's 14th and last Philippic.
• * Antony is again defeated in the Battle of Mutina by a coalition of Octavian, Decimus Brutus, and the two consuls of the year.
• Antony marches to Parma and Placentia. He then crosses the Ligurian Alps to Vada Sabatia, south-west of Genoa, and joins with Aemilius Lepidus, soon after Decimus Brutus is killed by brigands. The Senate declares Antony a hostis, an enemy of the state. Sextus Pompey becomes supreme commander of the Roman navy and Gaius Cassius proconsul of Syria.
• Summer - Gaius Cassius captures Rhodes after they refuse to pay tribute. Their fleet is defeated by Roman galleys in the Aegean Sea. He lands a military force on the island and plunders the city. Cassius puts to death 50 of the leading citizens and seizes all the gold he can lay hands on.
• July–August – Antony is again at the head of a large army; Octavian enters Rome in force without opposition. It is clear that Cicero's plan to divide them against each other has failed.
• August 19th – Gaius Octavian taking office as consul, the day before his 20th birthday, is prevailed to pass the lex Pedia, a law establishing the murder of Caesar as a capital crime.
• November 26 – Octavian meets Antony and Lepidus in Bononia and the three enter into an official five-year autocratic pact, the Second Triumvirate. To cement their reconciliation Octavian agrees to marry Clodia, a daughter of Antony's wife Fulvia by her former husband Publius Clodius Pulcher.
• November – The triumvirs introduce proscriptions in which allegedly 130 senators and 2,000 equites are branded as outlaws and deprived of their property.
• December 7 – Marcus Tullius Cicero is killed in Formiae in a litter going to the seaside, by a party led by Herennius and Popilius. His head and hands are displayed on the Rostra in the Forum Romanum.

  Gaul

• Lugdunum is founded.
• First reference to Cularo.

  Asia

• According to legend, Nagasena creates the Emerald Buddha figurine in Patna, India.