The Roman general who became dictator for life before his assassination was Julius Caesar. Rising through the military ranks, he gained immense power by leading successful campaigns in Gaul, which expanded Roman territory. His political alliances and reforms significantly altered the Roman Republic, including implementing the Julian calendar. In 49 BCE, he crossed the Rubicon River, sparking a civil war that ultimately led to his dictatorship. However, his concentrated power alarmed many senators, leading to his assassination on March 15, 44 BCE, known as the Ides of March. This act sparked further civil strife and ultimately contributed to the end of the Roman Republic and the rise of the Empire.