Marcus Vispanius Agrippa was Octavian’s friend and right hand man. He was instrumental in helping Octavian become the Roman Emperor Augustus. Octavian himself was physically pretty weak and thus entrusted Agrippa with command to fight in his stead. He fought in several battles for him, including the Battle of Actium where Marc Antony and Cleopatra were defeated. After Augustus’ ascension, he took a political career and was responsible for several buildings in Rome, including the Pantheon.
If you can't establish a new political order with your bestie after a brutal civil war, are you really even besties