This is the first appearance of the character of Gaius Julius Caesar, the most famous roman in history. At the time of the Spartacus Rebellion, Caesar was in his 20's. However, no historical accounts exist that he served under Marcus Crassus or was involved in quelling the rebellion.
Just before Spartacus sends Laeta to talk down her husband, he assures her that the Aedile won't be harmed before telling his men "I'm doing what I believe." He ends up killing the Aedile despite his claims and tells Laeta "I could not place faith in him." Since season one. Spartacus has made it clear that he held absolutely no faith in a Roman holding to his word and lived by that code. (As evidenced when he stood against Cossinius and Furius.)