Prelude to the Peloponnesian War | World History | Khan Academy

In the last few videos, we talked about the Greco-Persian Wars, or we could say the Persian invasion of Greece. In the first wave, the first Persian invasion, the Athenians were able to stop them at Marathon. Then, in the second Persian invasion, led by Xerxes, they were able to rout the Persian navy at Salamis and eventually get rid of the Persians altogether at Plataea in 479 BCE.

At that point, the Greeks, especially the powerful city-states of Sparta and Athens, were fighting on the same side. But, as we'll see in this video, this all starts to break down, and they will eventually be at war with each other in a very ugly war. You know, a lot of times when we think about these things thousands of years later, it might seem somewhat romantic—the stuff of stories and adventures—but these things are ugly. People are getting killed; people are getting tortured; civilians are dying. Whole cities are being destroyed.

Whenever we talk about history, it's very important to think about where your story is coming from. You should always have a nice dose of doubt on, well, what were the motivations of the person who wrote it? How much can they really know about things? When we talked about the Persian invasions of Greece, or the Greco-Persian Wars, that was coming to us from someone who is often known as the father of history. I guess that's a very Greco perspective, but that is Herodotus.

Now, we're going to start getting our accounts from someone who wrote the famous history of the Peloponnesian War, and that is Thucydides. They're so closely linked, especially because they're giving history of essentially this fifth century BCE, that this is actually a double bust of the two—Herodotus and Thucydides.

As soon as the Persians have been defeated and leave, you might remember that the Athenians had to escape to Salamis. That's where you also had the naval rout of the Persian navy. The Athenians decide, "Hey, let's move back to Athens." In deciding to move back to Athens, they say, "Okay, well, we want to build a wall around Athens in case anyone else wants to invade us."

You might say, "Okay, maybe they are somewhat concerned about the Persians," but you could also argue that they're somewhat concerned about the Spartans, who are famous for having this very powerful army. So they start the construction on what's often called the Long Wall. It's a way for them to have access to the sea and to protect their city in the event of a siege.

If you take the other side and think about what's going on in the minds of the Spartans, they are thinking, "Okay, you know, for a long time we were really the dominant military power." But what we've just seen with the Greco-Persian Wars is that this Athenian navy is actually quite strong. In some ways—and, in fact, in a lot of ways—you can argue that they're the ones who were able to beat off the Persians at Salamis; that the navy was essential there.

So Sparta is feeling a little bit threatened, and in particular, they don't like the idea of this wall. Here you have the city-state Athens with this very strong navy, and now they're building a wall. Sparta says, "Hey, if they have a wall, it's going to be very hard for us. If they think—if they start exerting too much influence, it's going to be hard for us to take down Athens."

They instead suggest, "Hey Athens, why don't you build a wall at the Isthmus of Corinth right over here?" You might notice the geography of Greece; you have this little— I guess you could call it this little strip of land that connects the mainland to this very large peninsula, which is called Peloponnesus, where Sparta is. You could imagine that this is a very strategic location. Anyone who wants to conquer the Peloponnesus by land is going to have to go through there.

But the Athenians, of course, say, "No, we care about protecting ourselves." And so they start to build this wall to protect themselves, which the Spartans are not so happy about. Now, the other thing the Athenians do is continue to build up their naval power. They see, "Hey, this is a very useful thing." They start connecting with a bunch of allies around the Aegean—some on islands, some on the coast of Anatolia over here.

They meet at the island of Delos, which you can't see here because it's a very small island, and they all agree to contribute their shared navies and to contribute money in order to continue to fight off the Persians wherever they are. You know, these Persians did this injustice to us, now let's go on the offensive. They form what is called the Delian League.

Now, once again, Sparta is not so happy about this because more and more it becomes clear that this Delian League—Athens isn't just a participant in the Delian League; Athens is starting to run the Delian League. When people try to drop out of the Delian League over time, Athens starts to exert itself. So the Delian League is really turning more and more into an Athenian Empire.

Once again, Athens proved itself. Its navy proved itself to be very powerful in this war. Sparta's getting insecure. Athens doesn't listen to Sparta about this wall and decides to start building it. Sparta is feeling even more insecure. Athens is starting to create this Delian League, which is really an Athenian Empire—making Sparta even more insecure—and it kind of gets a little bit more intense in 464.

There are some accounts that Sparta around this time was already planning to invade Athens to say, "Hey, these folks are getting too powerful; let's just put them in their place." But around that time, in 464, you have a major earthquake in Sparta, which demolishes large parts of the city. When that earthquake happens, the Spartan helots—who I guess the best way you can view them is they are slaves—(I encourage you to read more about them) were treated horribly. In Sparta, the accounts are that there were seven of these helots, or slaves, for every Spartan.

So, the helots start a revolt. Sparta goes to the other city-states of Greece and says, "Help us put down this revolt that happened right after our earthquake." Athens agrees; they send 4,000 citizen soldiers to Sparta, the citizen soldiers of famous hoplites, to help put down the revolt. But once again, Sparta is feeling insecure. They say, "Hey, why do they send these soldiers? Maybe they say they want to put down this rebellion, but we, Sparta, we're kind of in a fairly vulnerable state right here. What if the Athenians took the side of the helots? Well then, they might be able to take over Sparta."

So, they send the Athenian hoplites back. They say, "You know, we don't need your help." You could imagine the Athenians now are starting to take significant offense to how the Spartans are treating them.

Then, fast forward a little bit more to 459 BCE. You have two allies of Sparta, Megara and Corinth. They're right in this very strategic location—this little land connection, that land bridge, between the mainland and the Peloponnesus. There is a dispute between these two allies of Sparta, between Corinth and Megara, and Athens decides to intervene and form an alliance with Megara.

Well, you can imagine, you know, this insecurity has been building up in Sparta for at this point over a decade. It all comes to a head, and they start having skirmishes. They start essentially going to war with each other. They have these sporadic skirmishes over the next 15 years. This period, right over here—from roughly 460 or 459 for the next 15 years—this is often referred to as the first Peloponnesian War. Because, once again, you have Sparta and its allies starting to get into all these skirmishes with Athens and its allies.

But this isn't the Peloponnesian War; the main Peloponnesian War is going to come a little bit about 15 years later. The first Peloponnesian War that we're just talking about eventually ends with what's called a Thirty Years' Peace. This peace treaty only lasts for 15 years. But throughout that time, the Athenians' navy is growing more powerful. They keep getting in each other's way and annoying each other.

So, the Peloponnesian War, which we'll talk about in more detail, will occur at the end of the fifth century BCE and will conclude with Sparta being victorious. But in the process, most of Greece is significantly hurt, and all of the significant city-states of Greece are significantly weakened. That sets things up for the fourth century BCE, where it leaves the city-states of Greece vulnerable to an attack from the North, in particular Macedonia. We'll see that actually in several videos in the future.