The die is cast. Caesar crosses the Rubicon with his troops: the showdown begins. The time of the ensuing civil war between Caesar's supporters and the majority of the Senate under Pompey is described by the general himself in the three books 'Commentarii de bello civili'. It concludes with the decisive battle of Pharsalus in 48 BC, where the Senate majority is defeated. Caesar's former ally and son-in-law, Pompey, flees to Egypt and meets his end there. 'De bello civili' is a central source for the study of the history of the Roman Republic.