The naval battle of Actium (31 BCE) is an interesting example of a conflict that can, for one side, be a defeat and a victory at the same time. The Romans were fighting a civil war. On the one hand was Marc Antony, supported by queen Cleopatra VII of Egypt and 23 legions; on the other hand were Octavian, his friend Agrippa, and 24 legions.
Because Agrippa cut off Antony’s lines of contact, his army was beginning to suffer from hunger, and Antony decided to break away from Actium. He succeeded – and seen from this persepective, Actium was a victory. But at the same time, he had suffered a strategic defeat, because he had lost his army, had lost his reputation as an honest commander who would never abandon his men, and had lost any chance to win the war. In 30, Marc Antony and Cleopatra committed suicide, and Octavian became sole ruler of the Mediterranean world.