Explanation: After Caesar had conquered Gaul, his term of governorship was over, and he was vulnerable to prosecution by his political foes. As a populare, a supporter of the lower classes, he had made many enemies amongst the optimates, the reactionaries, who scuttled an acceptable compromise which would have allowed Caesar to not be executed for nebulous reasons. Given the choice of being executed or waiting for the Senate to muster their armies and march on him, he chose a third option - to overthrow the Senate which threatened him.
Explanation: After Caesar had conquered Gaul, his term of governorship was over, and he was vulnerable to prosecution by his political foes. As a populare, a supporter of the lower classes, he had made many enemies amongst the optimates, the reactionaries, who scuttled an acceptable compromise which would have allowed Caesar to not be executed for nebulous reasons. Given the choice of being executed or waiting for the Senate to muster their armies and march on him, he chose a third option - to overthrow the Senate which threatened him.