The Commentaries on the Civil War are Julius Caesar's own account of his conflict with Pompey and his allies in the Roman Senate during 48-49BC. The famous 'crossing of the Rubicon' is downplayed in Caesar's version of events, presumably because he did not wish to dwell on the constitutionality of his own actions as a Roman general bringing his army into Italy. instead, the emphasis is placed on his opponents responsibility for precipitating events by their attacks on the people's tribune, Mark Anthony, who fled to Caesar's army for protection.
The bulk of the narrative is concerned with the campaigns which followed. Caesar quickly swept the Pompeians to the heel of Italy, besieging them at Brundisium, from where their main force escaped across the Adriatic. Caesar and his lieutenants then turned to deal with Pompey's armies and allies in a variety of other theatres including Spain, Massilia in southern Gaul, Sicily and North Africa.
The decisive campaign in the Balkans saw Caesar facing defeat at Dyrrachium before his ultimate victory at Pharsalus. The Commentaries end with Caesar's army in Egypt following the murder of the exiled Pompey by King Ptolemy. Subsequent events are the subject of the Commentaries on the Alexandrian War.
Despite his apparently objective style, Caesar's propaganda purpose is more obvious than in the Gallic War, notably in his description of the wrangling for Roman political offices in the Pompeian camp in the days before the Battle of Pharsalus.
Gutenberg: "De Bello Gallico" and Other Commentaries by Julius Caesar, translated by W.A. McDevitte. Multiple formats.
Internet Classics Archive: The Civil Wars, Translated by W. A. McDevitte and W. S. Bohn. Online version with downloadable .txt version.
LacusCurtius: Caesar - The Civil Wars. Online version of English translation by A.G. Peskett, 1914.
Latin Library: C. IVLI CAESARIS COMMENTARIORVM DE BELLO CIVILI - Latin text, HTML format.
Textkit: Caesar's Civil War in Latin, edited by Charles Moberly. Pdf file. Seems to be missing first page of the Latin text.
Wikisource: Commentaries on the Civil War. HTML text.
BBC Radio Great Lives: Julius Caesar. Matthew Parris with Barry Cunliffe.
Internet Archive: Commentaries of Julius Caesar - audiobooks of The Gallic War and The Civil War.
Librivox: De Bello Gallico Libri Septem - public domain audiobook in Latin.
MCGoodwin.net: Summary of the Commentaries on the Civil War by Michael Goodwin.
Perry-Castañeda Library Map Collection: Maps from Dr. Butler's Atlas of Ancient Geography by Samuel Butler, London: Longman, Brown, Green, and Longmans, 1851. A number of these maps are useful for following the campaigns of the Civil War.
Wikipedia: Commentarii de Bello Civili.
The Great Conversation: Further reading at Tom's Learning Notes
Caesar: Commentaries on The Gallic War.
Caesar: The Alexandrian War.
Caesar: The African War.
Caesar: The Spanish War.
Lucan: Pharsalia - A Latin epic on the Civil War from a republican point of view.
Plutarch: Life of Caesar in the Parallel Lives.
Suetonius: Life of Caesar in Lives of the Twelve Caesars.
Butler's Atlas of Ancient Geography, particularly Africa (3.2 MB) | Egypt (3.3 MB) | Gallia (France) (4.0 MB) | Greece and Islands (3.6 MB) | Greece and the Peloponnese (4.3 MB) | Greece and the Peloponnesus, South (3.8 MB) | Islands in the Aegean Sea (4.5 MB) | Italy, Central (3.8 MB) | Italy, North (4.1 MB) | Italy, South (3.7 MB) | Macedonia, Moesia, Thracia, and Dacia (4.1 MB) | Mauritania, Numidia, and Africa (3.2 MB) | Rome (3.9 MB) | Spain (3.9 MB) | Vindelicia, Rhaetia, Noricum, Pannonia, and Illyricum (3.0 MB)
Latin Resources: Online materials for learning Latin.