How did Caesar Conquer Gaul and Destroy the Republic?

Caesar had been appointed as dictator back in Rome despite being in and out of Italy as a whole to engage in campaigns in the Middle East and Africa as well as his endeavors in Asia. He was also repeatedly named consul and his dictatorship renewed multiple times, having pardoned his enemies in the Senate and thus laying claim to very few opponents at home. Once he finally returned to Rome again in the 40s BC, Caesar began to roll out new legal reforms, even changing the Roman calendar. He was essentially the sole authority in the crumbling Roman Republic if one could even still call it that, holding the titles of dictator, tribune, and consul.