The law that granted Caesar a five-year command in Gaul was the Lex Vatinia. Passed in 59 BC, it made Gaius Julius Caesar governor of Cisalpine Gaul and Illyricum for five years.
The law was proposed by Publius Vatinius, a plebeian tribune, during Caesar’s first consulship. It also assigned Caesar three legions and allowed him to appoint his own legates, giving him both military authority and considerable independence from the Senate.
Caesar’s provincial command became the foundation of his conquest of Gaul. After the initial five-year period, his allies—including Pompey and Crassus—helped extend his command. Caesar used the armies and wealth gained during these campaigns to become Rome’s most powerful military and political figure.
The Lex Vatinia is sometimes confused with later laws connected to Caesar’s provincial extensions, but it was the original measure that established his five-year command.