Gallic Wars

The Gallic Wars were military campaigns waged by the Roman proconsul Julius Caesar against tribes in Gaul between 58 BC and 50 BC. The wars gave Rome rich farmlands in Gaul (roughly France and Belgium up to the Rhine).
Caesar's sub-commanders included Mark Antony, Titus Labienus, Quintus Tullius Cicero (brother of Marcus Tullius Cicero), Publius Licinius Crassus (brother of Marcus Licinus Crassus, the richest man in Rome), Decimus Brutus Albinus and Servius Sulpicius Galba (praetor 54 BC).
Julius Caesar described the Gallic Wars in his book "Commentarii de Bello Gallico". This is the main source, but it makes impossible claims about the number of Gauls killed (over a million), while claiming few Roman casualties. Modern historians believe that Gallic forces were far smaller than Caesar claimed, and that they (the Romans) suffered tens of thousands of casualties. One of the leaders of the Gauls, Vercingetorix, was taken to Rome, and later executed.
The main contemporary source for the conflict is Julius Caesar's "Commentarii de Bello Gallico". This was thought to be truthful and accurate until the 20th century. Even in 1908, Camille Jullian wrote a comprehensive history of Gaul and took Caesar's account as absolutely true. But after World War II, historians began to question if Caesar's claims stood up.
Modern estimates are that at the battle of Alesia, in 52 BC, there were about 70,000 Gauls, and the same number of Roman troops. That is still a very large number, in a world with far fewer people than is the case today.