Plutarch begins his biography of Philopoemen by describing his background, characteristics, and goals. Philopoemen is born into a good family from Megalopolis, but he loses his father when he is young and is brought up by his father’s friend Cassander. From a very early age, Philopoemen is determined to become a great general. When Philopoemen is 30 years old, the Spartan king Cleomenes takes Megalopolis in a surprise attack. The Macedonians agree to help the Achaeans of Megalopolis retake their city. Antigonus, the Macedonian king, is annoyed that Philopoemen monopolizes command, but admits that he is professional and skilled as a general.

Philopoemen declines an offer to join Antigonus’s army as a commander. He spends some time in Crete gaining military experience. When he returns home, the Achaeans make him a cavalry commander. Philopoemen instills discipline and passion, first in his men and then in all the citizenry of Megalopolis. The people even melt down their household utensils to make new weapons. With morale at an all-time high, the Achaeans are confident that they will win their war against the Spartans and regain their former glory. Philopoemen faces the Spartans at the Battle of Mantinea, where his skill wins an important victory.