Question

Why does Mark Antony describe Brutus as “the noblest Roman of them all” (5.5)?

Answer 1

Mark Antony describes Brutus as "the noblest Roman of them all" because Brutus is the only conspirator who acted for the good of Rome, rather than out of jealousy, bitterness, or a thirst for power. 

Answer 2

After the death of Julius Caesar by the hand of a group of conspirators, including Marcus Junius Brutus, Rome and all its provinces, fall under the joint control of the Second Triumvirate, led by Mark Antony, Octavian and Marcus Lepidus. Because of the conflict that arises after the assissination and the desire on one hand for power and the other for a return to a Republic, as it was before Caesar took total control of it, Brutus and Gaius Cassius Longinus gather 19 legions and march towards Rome but are met by the armies of Mark Antony and Octavian in Phillipi, the epitome of the Liberator´s civil war, in the Battle of Phillipi. Two confrontations ensue and on the final one, on October 23rd, 42 BC, Mark Antony defeats the forces of Brutus and the latter commits suicide. In the end, instead of desecrating the body of Brutus as it would have been expected, Mark Antony goes to compliment Brutus´s efforts and actions because according to Mark Antony, Brutus was the only conspirator who acted in the name of the greater good, on behalf of the welfare of the Roman people, instead of simply being jealous of Caesar´s power. However, it is also to be understood that this compliment paid by Mark Antony to Brutus comes joined by the irony in the words used, as not long before Mark Antony had ended Brutus´ efforts.