The entire war was meticulously documented by the historian Thucydides for his work History of the Peloponnesian War. This work was followed by Xenophon in his Greek History.

The Athenian Naval Association was a grouping of free Greek states formed after the end of the Greco-Persian Wars. It later became a power bloc that promoted the interests of Athens. Athens built the so-called "long walls" connecting the city to its port of Piraeus, making the municipality immune to attacks from the mainland. On the other side was the Peloponnesian bloc, led by Sparta.

The war between Athens and Sparta between 457 and 446/445 BC, triggered by the defection of Megara to Athens, is often considered the prelude to the entire Peloponnesian War.

However, the initial impetus for the war was the alliance of Thebes (Athens' northern neighbour) and Sparta, which was directed against Phocis (Athens' ally). When Sparta sent troops to Boeotia, they were opposed by Athens, which was defeated by Sparta (Battle of Tanagra). However, two months later, Athens defeated Thebes at the Battle of Oinophyta and thus became the dominant power in central Greece for the next ten years. Later, however, Athens had to recognize the autonomy of Boeotia, bringing the war to a stalemate. Subsequently, Megara changed sides again and joined Sparta. The forces were thus equalized and a thirty-year peace treaty was written.

This treaty was broken when neutral Corinth greatly strengthened its navy and sought to establish hegemony in the Ambracian Gulf. As part of the Epidamnus War, the Democratic Party called on the aid of Corinth and the aristocracy of the former Corinthian colony of Kerkyra. This created a war between Corinth and Kerkyra for dominance of the Ionian Sea. Corinth continued to strengthen its fleet, however, threatening Athens, which would then lose its status as the greatest naval power. Athens therefore formed a defensive alliance with Kerkyra. Corinth, however, saw this as a violation of the peace of 446 BC and turned to Sparta.

Another problem was the dispute at Poteidaii on the Chalkidiki peninsula. Poteidaia was an ally of Athens but maintained good relations with Corinth as well. Athens called on Poteidaia to expel Corinthian officials and to demolish its harbour fortifications. Whereupon Poteidaia withdrew from the naval association. Despite the support of Corinth, she was besieged by the Athenians shortly afterwards.

Moreover, at that time, the Athenian People's Assembly passed a resolution to establish a naval blockade of its ports because of the dispute with Megara. Megara thus asked for help from her allies, namely Sparta. This was effectively the beginning of the Peloponnesian War.

In the summer of 432 BC, Sparta was invited to join the war. King Archidamus II urged a reasonable solution, but failed. A formal declaration of war followed. Athens had a weaker ground army, but protected the population of Attica behind "long walls" that were indestructible at the time. They also had a powerful navy. Sparta, on the other hand, had a clear superiority in ground troops.

The first military clash was carried out by the Spartan allies, the Thebans, with an attack on the Plataea in early 431 BC.

The Athenians were thus reluctant to engage in a military clash on land, and sought to use their fleet to attack the coastal cities of the Peloponnese and slowly exhaust Sparta by blocking the sea routes. Sparta used a similar tactic, periodically attacking Attica, which it burned entirely and then after a few weeks its troops pulled out. They were trying to lure the Athenians into open battle.

After the death of Pericles, Cleon and Nicias took over the Athenian government. They pushed for a further extension of support to the poorer classes of the people, as much of the population of Attica had been gathered inside Athenian fortifications for some time and their possessions had been left at the mercy of the Spartans. This, however, put a great strain on the Athenian budget.

Even in the following years of the war, it was not clear who had the upper hand.

However, in 425 BC, part of the Athenian army under the command of the strategos Demosthenes landed at Cape Pylos on the western coast of the Peloponnese and fortified it. The Spartan siege was unsuccessful and in addition 120 Spartiates (elite warriors) were taken prisoner at the Battle of Sphakteria. After this heavy defeat, Sparta offered peace to Athens. The agreement was not confirmed because Athens demanded unacceptable territorial concessions.

Subsequently, the Spartans, fearing for the fate of the captured soldiers, abandoned further raids into Attica. And focused on weakening Athens by attacking its allies.

In 424 BC, Sparta went on a campaign into Thrace. Arriving north, Sparta forged an alliance with the hitherto neutral Macedonian king Perdiccas II. With this support, the Spartans took control of the city of Amphipolis, the most important Athenian foothold on the northern Aegean coast. Moreover, in the same year, Athens lost a land battle with Thebes. As a result, Athens had great difficulty protecting its grain supply from the Crimea or its gold and timber supplies. Athens was subsequently divided between demanding a hard blow against Sparta (Cleon) and demanding a reconciliation with Sparta (Níkias).

At the Battle of Amphipolis in 422 BC, the Spartans were victorious, but both Cleon and the Spartan warlord Brásidas fell. The death of these hardliners opened the way for a peace treaty, named the Peace of Nicias after its architect.

At the time of the peace, Alcibiades persuaded Athens to go to Sicily to cut off Sparta's grain supply and expand the Athenian sphere of influence. A request from Segesta for help against Syracuse served as a pretext. Alcibiades managed to win this war, but on his return to Athens he was to be tried for allegedly defacing statues of the god Hermes. So instead of returning to Athens, he sided with Sparta, which was the beginning of the end of Athens.

Nicias continued to besiege Syracuse, but was unable to completely encircle it. Sparta dispatched a small detachment of soldiers to its ally, led by the experienced Gylippus. Nicias' attempts to take the city continued to be unsuccessful despite the reinforcements that arrived. The situation continued to deteriorate until the Athenian fleet was cut off in the Gulf of Syracuse and eventually destroyed. Consequently, Athens had to withdraw, but this decision came very late. And so most of the army fell into captivity, in which many of them died. The commanders Nikias and Demosthenes were executed.

Athens was weakened, and although the forces remained balanced, Sparta declared in 414 BC. The peace of Nicias was broken. Then, taking Alcibiades' advice, it occupied the city in 413 BC. Dekeleia, a strategically important village in Attica, which from this point on served as a base for the Spartans to raid the Athenian area. Athens was thus permanently besieged, causing the flight of slaves, but more importantly the loss of supplies from the island of Euboea. These had to come only by sea. Even the army had to permanently protect the long walls, which tied up a considerable number of soldiers to defend the city.

In addition, Athens supported a local rebellion in Asia Minor in 414 BC, which antagonised the Persian Empire. The Persians allied themselves with Sparta, which ceded Asia Minor to them, in return for which the Persians promised to pay them regular monetary payments. With this money, Sparta began to build a powerful fleet. This gradually became as strong as the Athenian, but there was no major victory for either side. This was also because the Persians were comfortable with the conflict and tried to prolong it, as this weakened both sides, which was to Persia's advantage.

Alcibiades decided not to serve Sparta at this time and considered returning to Athens. Here, however, a coup was being prepared to remove democracy and introduce an oligarchy. This pressure paid off for the conspirators and their aims were achieved. But it did not bring peace with Sparta or Persia.

Moreover, although the commanders were supporters of the oligarchy, the rowers, for example, were supporters of democracy and refused to support the new government. And so, after a few months, the Council of Four Hundred was dissolved. Alcibiades had already switched to the Democratic Party.

After the return of Alcibiades, Athens scored many victories. After the battle of Kyzicus, Sparta was again ready to accept peace, but Athens (led by Cleophonous) refused. Alcibiades, despite his recent defection to Sparta, was elected chief strategos with almost unlimited power.

On the Spartan side, General Lysandros made close contact with the Persians and induced them to put a definite end to their hitherto cautious policy and decide to support Sparta fully. The effect was felt almost immediately when Athens was defeated at the battle of Notia. Alcibiades was subsequently removed as strategos.

Athens was victorious in the greatest naval battle of the Arginus Islands, but because it neglected to rescue the drowning sailors, the famous Arginus Trial occurred. In it, several victorious Athenian strategists were executed, depriving Athens of experienced commanders.

The following year, Athens fell at the Battle of Aigospotamoi. Athens then no longer had a fleet, and the Spartans dominated the sea. Athens was also abandoned by its allies (except for the island of Samos). Sparta then attacked Samos and Athens by land and sea. They were completely starved and capitulated in 404 BC. Athens realised only too late that it should have treated its allies as equals and not as subordinates.

"After accepting the terms of peace, Lysandros entered Piraeus, and then the breaking down of the walls was begun with great ceremony, accompanied by the music of flute players, for it was believed that this day marked the beginning of the freedom of the Hellenes."

Subsequently, the Athenian naval association was dissolved, the fleet was handed over to Sparta and eventually burned. A Prospartan oligarchic government of thirty tyrants was established in Athens, which was overthrown in 403 BC. Similar governments were established in other Greek communities. Corinth and Thebes sought the complete destruction of Athens, but this was rejected by the Spartans, because it was these two municipalities that would benefit most from the destruction of Athens.

Sparta, however, also had a problem, having promised to sacrifice the Asia Minor villages to Persia. However, this was not an option and this started Sparta's war with the Persian Empire.