In spite of being pardoned by Caesar and allowed to return home, Marcus joined his brother-in-law Brutus and his ally Gaius Cassius Longinus, who both assassinated Julius Caesar on March 15, 44 BC. Afterwards they fled Rome headed for Greece, where Marcus Cato fought in both of the battles of Philippi. He was killed in the second battle of Philippi in 42 BC (at the age of 31). According to Plutarch, as the army of the Liberators routed, Marcus refused to retreat and instead charged into the enemy ranks, allegedly without helmet or armor, to meet his death.