Diocletian took over a Roman Empire on the verge of total collapse — racked by civil war, economic crisis, and barbarian invasion — and rebuilt it so thoroughly that it survived another century in the West and a thousand more in the East. Then he did something no Roman emperor had ever done: he voluntarily abdicated and retired to a palace in Split to grow cabbages. When former colleagues urged him to return to power, he told them they should see how fine his cabbages were.

This episode traces Diocletian from his rise through the military ranks through the Tetrarchy, the Great Persecution of Christians, the economic reforms that stabilized the empire, and the abdication that remains unique in Roman history.

• Diocletian’s rise from obscure Dalmatian soldier to sole ruler of the Roman Empire
• The Tetrarchy — dividing imperial power among four rulers to prevent civil war
• The Great Persecution of Christians and the economic reforms that rebuilt the empire
• The unprecedented voluntary abdication and the retirement to his cabbage garden in Split