Even though this work is a non-Socratic work, it seems everywhere to suggest the influence of Socrates: everyone talks in a Socratic way, and some of Cyrus's excellences are clearly understood in Socratic terms. And there seem to be a number of ways in which Xenophon deliberately adjusts Cyrus to give him a Socratic hue.
You can read the Cyropaedia online in English at the Perseus Project. There is an online collaborative commentary on the work called Cyrus' Paradise, which has a number of interesting discussions.
Book I sets the theme of the work and gives us the first basic education of Cyrus. Xenophon begins by noting that all sorts of governments are often overthrown by the people who are ruled by them, so that it seems that human beings have no art by which to rule other human beings. However, having thought of this, he also thought of Cyrus the Great, "who acquired very many people, very many cities, and very many nations, all obedient to himself" (1.1), and that the obedience was given despite vast distances and differences in language and culture. So what is the secret to a Cyrus? This is what the rest of the work will discuss.
Cyrus is said to have been the son of Cambyses, king of the Persians. He was educated in the laws of the Persians, which are very focused on what is common rather than what is individual. (Xenophon's account of Persian education is very clearly a slightly adapted account of Spartan education.) Cyrus only had this education until he was about twelve; at that age his grandfather on his mother's side, who was king of the Medes, sent for his daughter and grandson. Thus he learns the ways of the Medes, which are rather different. As Cyrus's mother, Mandane, puts it, in Persia being equal is what is accounted just, and the law rules the king, whereas in Media the king is master of all and ruled by no law. Because Cyrus loved to learn, he grew adept in the ways of the Medes. Then he returned, before fully adult, to Persia. Soon his grandfather in Media died, and was succeeded by Cyrus's uncle Cyaxares. At this point, the king of Assyria, seeing a possible opportunity, began to plan to defeat the Medes, and to that end started building an alliance. Cyaxares sent to Persia for help, and so Cyrus found himself in Media again, at the head of an army. After taking thought to the gods and offering sacrifices, he receives some advice from his father about caution and preparation. His father also gives him advice as to how to make soldiers obey. After Cyrus remarks on the importance of praising those who obey and punishing those who disobey, Cambyses says:
"Yes, son, this is indeed the road to their obeying by compulsion, but to what is far superior to this, to their being willing to obey, there is another road that is shorter, for human beings obey with great pleasure whomever they think is more prudent about their own advantage than they are themselves....Yet whenever people think that they will incur any harm by obeying, they are not very willing either to yield to punishments or to be seduced by gifts, for no one is willing to receive even gifts when they bring him harm." (1.6)
Being prudent about advantage, however, can only be learned by actively learning what you can. And while it is true that always doing good for someone will tend to win them over, it is nonetheless difficult to do this. Thus a ruler must rejoice at good given to others, grieve at evils that befall them, be enthusiastic about joining them in solving their difficulties, and carefully plan to avoid failure. The ruler must have more endurance than the ruled. As to enemies, the only way to maintain power over them is to "be a plotter, a dissembler, wily, a cheat, a thief, rapacious, and the sort who takes advantage of his enemies in everything" (1.6). Cyrus notes that this is the opposite of what everyone is taught as a boy, and Cambyses notes that many of the things one learns as a boy has to do with the treatment of friends, not of enemies, for the same reason that we wait to teach boys explicitly about sex rather than doing so immediately (i.e., they do not yet have the restraint required); but in fact, boys are also taught to deal with enemies, just not by practicing on enemies. They learn to hunt, to trap, to outmaneuver, to deceive, in games and sports like the hunting of deer.
When Cyrus gets to Media he learns that the Assyrian king's alliance has grown considerably, and that the army that is coming against the Medes is huge in comparison with anything they can field. This is a problem, since both sides are heavily stocked with archers and spearmen, which suggests distance-skirmishing. But skirmishing at a distance tends to favor the more numerous army. Thus Cyrus argues that they should armor their Persian Peers, a relatively small but very well trained group, so that they can close the distance and force close quarters. This will put the opposing enemy in a bind by making it in their interest to flee rather than to continue to fight. In addition, Cyrus lets any common soldier who wishes have a chance to receive honors like those of the elite soldiers. They train in fighting at close quarters, and he holds contests for those who fight well and obey orders to receive higher rank. He forces them to bunk together so that they will see that everyone is treated equally and, in addition, will be more likely to be ashamed not to fight if they know who else is fighting. He dines not just with officers, but with anyone whom he sees as doing well what they should be doing.
After discussion with people over dinner, Cyrus decides to put it to the army whether it will be better for everyone to share equally or for those who work hardest to receive the better share. A number of people respond with speeches (including one by Pheraulas, one of the common soldiers), and the general consensus is that it is better for those who work hardest to receive more -- as Cyrus had expected, people are ashamed to suggest that they should receive an equal share even if they do less, or do their work poorly.
Cyrus proposes to Cyaxares that they should secretly go against the king of Armenia. He is not technically part of the Assyrian alliance, but as the alliance has grown he has shown an increasing tendency to show contempt for the Medes, neglecting to provide tribute or support. Under the guise of a big hunt, Cyrus goes forth with his cavalry, and at the border of Armenia he lets his officers in on the plan. He has part of the army go forward dressed as if they were bands of robbers, to reduce the chance of the Armenians having early notice of the full army and hiding away in the mountains. The robber-dressed part of the army is also there to impede the flight to the mountains should it come to that. Cyrus in the meantime will go against the Armenians directly with the main cavalry.
Cyrus sends to the Armenian king and demands that he do what needs to be done to make up for tribute and lack of military support; the Armenians, caught by surprise, are found running around pell-mell trying to hide away their possessions or get their families to safety; Cyrus promises that those who stay will not be considered enemies, but those who run away will be treated as such. In the meantime, the king's own family is caught in flight to the mountains and the king is besieged; he surrenders and is put on trial by Cyrus. The Armenian king is forced to admit that he would be harsh with any subordinate who did as he had done, but the Armenian king's son, Tigranes, argues that Cyrus should only punish when it is in his interest to punish -- and the Armenian king, having been shown that he can easily be beaten, is now more useful as an ally than as someone to be punished. Cyrus agrees, and asks the Armenian king what he will do to show himself useful. Thus Cyrus comes away with more troops for the fight and also a considerable amount of money, given to ransom the family.
Taking away the Armenian troops, led by Tigranes, Cyrus comes to the mountains on the borders of Armenia, which are controlled by the hostile Chaldaeans. They go against the Chaldaeans. Tigranes warns him that the Armenians will not press the matter all the way, but he incorporates this into his plan by telling the Persians that the Armenians will pretend to flee in order to tempt the Chaldaeans into close-quarters combat. When the Armenians do really flee, as Tigranes had said they would, the Chaldaeans pursue (as they are accustomed to doing with Armenians in the mountains) and the Persians mop them up. Cyrus then uses his leverage with the Chaldaeans, who are now worried about what Cyrus will do, to establish and force a peace treaty between the Chaldaeans and the Armenians, which will be enforced and supervised by the Persians; he is careful to make sure that each side gets something that they need, as a real practical matter, from the peace -- in particular, the Chaldaeans have a labor shortage and the Armenians a labor glut -- and also from the Persian supervision, since if the Persians hold the key points they don't have to worry about the other side using the strategic advantage to retaliate against the other side. He then uses this collaboration between Chaldaeans and Armenians to pull the Indians, who have been temporizing about who to support, on to the Persian side. Cyrus needs money, he tells them, but given that they are new-found friends, he'd rather not have to take theirs. So he recommends that each side send messengers to the Indians playing up the value of supporting the Persians.
Back with the Medians, Cyrus recommends going on the offensive: as long as the armies are in Median territory, there is inevitable damage done to Median territory. There are no real advantages to waiting -- they will still be outnumbered even if they wait -- but by pushing on into enemy territory they will be doing damage to the enemy, even if it is just unsettling them by how ready the Medes and the Persians are to fight. One of the things they do as they advance is only cook during the day; at night no campfires are allowed in camp. They also sometimes burn campfires at night far behind the actual camp. Thus the enemy scouts are in constant confusion about where the army actually is. The Assyrians usually defend their camps by digging trenches around them; thus the Assyrian army made their camp where it would be convenient to dig trenches -- and at this point it just so happened that the best place was in full view. Cyrus, however, deliberately camps his army in the place where the Armenians will be least likely to see what he is doing, so that he could spring something on them suddenly.
Cyaxares and Cyrus, who have largely been in agreement up to this point, disagree about the best tactics for the situation. Cyaxares wants to try to intimidate the enemy by assaulting the fortifications. Cyrus, however, argues that this will not work, for the Assyrians will trust their fortifications and see that they outnumber their enemy. In addition, any failure will give the Assyrians heart. He recommends that they wait until the Assyrians themselves come out. This is agreed upon, and the Assyrians do indeed prefer to come out rather than sit in camp. Cyaxares wants to assault the first group out, but Cyrus insists that it will be as good as a loss if less than half the Assyrians are defeated; if they fight too small a group at first, the Assyrians will get a second chance at coming up with a battle plan and will be able to pursue the second battle on their own terms. Cyaxares is not convinced, and presses Cyrus to move; Cyrus instructs his returning messenger to tell Cyaxares in front of everyone that there are still too few, but he will comply. The Persians rush the Assyrians, who turn to flee to the fortifications. The Medes and Persians press, but Cyrus pulls back the Persian Peers before they get caught inside the fortifications themselves, and the fact that they obeyed Xenophon notes approvingly as a sign that they were properly trained.
The Assyrians, having lost the leaders of their army, flee in the night, leaving behind their provisions. He opposes pursuing the Assyrians, saying that they lack the horses required for such a task. At this point there just happens to arrive an embassy from the Hyrcanians, who are subjects of the Assyrians. Because the Hyrcanians are good with horses, the Assyrians use them for hard cavalry work. Hyrcanian cavalry had been guarding the Assyrian retreat. But the Hyrcanians see that this is a possible opportunity for breaking free of the heavy Assyrian yoke, so they offer their services to Cyrus, providing information as a show of good faith. Since the Hyrcanians tell them that the Assyrians can be caught before reaching their strongholds, if only one starts early enough and leaves behind heavy gear, this raises new possibilities. The Hyrcanians offer to bring hostages from stragglers among the Assyrians, to prove that they are right, and Cyrus promises that the Hyrcanians will have equal place with the Medes and the Persians if they give him their support. Cyrus asks for volunteers, and all the Persians and most of the Medes are willing to do so, especially when the latter hear about the Hyrcanians. The Hyrcanians realize that Cyrus is trusting them without requiring that they bring any hostages as proof of their word, as they had said they were willing to do, and are astonished. But Cyrus tells them that they have all the guarantee they need in their souls and in their preparation; although he does happen to mention the fact that if the Hyrcanians were to betray him, the Hyrcanians are the ones who would be at a disadvantage. This is actually the single best reply he could have made -- the Hyrcanians are impressed, even a bit frightened, at the fact that Cyrus is so confident about not needing to worry about the matter, and when the Persians and Medes catch up to the main Hyrcanian forces, they are equally impressed by the ease with which Cyrus treats them as allies worthy of trust, who are to be brought in not out of desperate need or through force, but simply by being asked to do so as allies.
The alliance of Persians, Medes, and Hyrcanians quickly overtakes the alliance armies, putting them into disarray. When Cyrus captures the camp servants, he realizes an opportunity to have appropriate provisions for his men, so he has them set aside provisions, which they are willing to do for the obvious reason that they see it as a way to keep from dying. Cyrus convinces the Persians to let the Medes and Hyrcanians be in charge of distributing the loot, even if they get less by it. The loot ends up being quite considerable, as are the number of female captives, because, says Xenophon they claim that soldiers will fight more fiercely if what they regard as precious is present. Xenophon is skeptical; as he says drily, "Perhaps this is so, but perhaps they also do this because they take delight in the pleasure" (4.3).
Cyrus takes the occasion to argue that the Persians should develop their own cavalry, and Chrysantas, one of his captains, agrees, saying that he has always envied the centaurs. As a result, they all agree that it will be a law among them that whoever is given a horse by Cyrus will regard it as shameful to be seen on foot, until people start to wonder whether the Persians might not actually be centaurs. This starts a custom that Xenophon says has continued until his day. He then turns his attention to the captives who are starting to come in. Cyrus points out that even good land is useless without people working it, and so he proposes that they release the captives , and to the captives says that they will be allowed to go home, on condition that they promise not to fight against the Persians and the Medes again; and in the future, if anyone does something unjust to them, the Persians and the Medes will fight on their side. Obviously the captives promise.
Cyaxares, somewhat hilariously, has been unaware of what was happening, since he has been partying in his tent after the first victory over the Assyrians. He has quite a surprise when he comes out the next morning, and is not at all happy about it. When he discovers the whole story of the Hyrcanians, he is even more furious, and recalls the Median cavalry by sending a small contingent of what he has left. The Medes are uncertain as to what to do, since he obviously has the right to call them back, but is also famously savage when angry. Cyrus sends a messenger to Persia, asking for reinforcements, and leverages his new alliance with the Hyrcanians by having them keep the contingent of Medes in charge of the recall entertained. He then sends a message to Cyaxares reporting what has happened. Cyrus does as he intended and puts the Hyrcanians and Medes in charge of distribution of loot. They give the horses to Cyrus, and he tells them to give generously to Cyaxares, as well. He then frees anyone who had been enslaved by the Assyrians in exchange for joining the ranks.
At this point, a captured Assyrian named Gobryas is brought in and asks to speak to Cyrus. He was good friends with the old Assyrian king, who had died in the battle at the fortifications, and was not on good terms with his son, the new Assyrian king, since he had caused the death of Gobryas's son. Gobryas asks Cyrus to become his avenger, and Cyrus promises he will, and will let him keep all that was his, if Gobryas can prove he is not lying. They agree, and Gobryas is allowed to return home. In the meantime, the distribution is done; the Medes have given Cyrus the most beautiful tent and the most beautiful woman, the Susan woman. The Hyrcanians gave the extra tents to Cyrus and distributed the coined money fairly.
The saga of Cyrus is, of course, far from over, and we will see both the Susan and Gobryas, as well as the response of Cyaxares, in the next books.