When king Darius II of Persia died, both of his sons, Artaxerxes and Cyrus, wanted to be king. But Artaxerxes made himself king by force. Cyrus decided that he would raise an army and demand Artaxerxes to step off the throne.
Cyrus couldn't find enough Persian soldiers, so he hired eleven thousand Greek soldiers. In the middle of the battle, Cyrus was killed and the Persians on his side surrendered. But the Greeks continued fighting. Artaxerxes sent a message telling them that Cyrus was dead and gave their leaders an invitation to their council.
When the Greek leaders arrived, they were killed and a message was sent to the Greeks. It told them that their leaders were dead so they now had to fight in the Persian army. The Greeks were both enraged and grief-stricken when they heard this. The Greeks thought that they were going to die and they would never see Greece again. They wouldn't eat their supper and couldn't sleep because they were so sorrowful.
However, Xenophon was thinking of a way that the army could return to Greece. He was a pupil of Socrates, a famous philosopher. While everyone else was in despair, he found a way that they might get back to Greece. They could appoint a leader and retreat to the ocean.