When in 431 BC the Peloponnesian War broke out, none of the belligerents could have imagined that they would be involved in the longest and most ferocious civil conflict. The ferocity of the new civil war would indeed exceed in ferocity any previous one. For the first time in their history until then, the Greeks would slaughter each other with such fanaticism.
The first businesses
In June of the same year, the king of Sparta, Archidamus, invaded Attica, at the head of a powerful Peloponnesian army. After capturing the border fortress of Oinoi, he plundered the countryside between Parnitha and Penteli for a month and then returned to the Peloponnese. The Athenians responded to this attack with a retaliatory raid on Laconia.
The strongest part of the Athenian fleet – 100 ships and the corresponding passengers – headed for the Peloponnese and plundered its coasts. Another squadron headed north and attacked the Spartan allies Locrus.
At the end of the summer, the Athenians attacked and captured Aegina, while in September they attacked Megaride and devastated it. The same situation was repeated in the second year of the war, the most important event of which was the outbreak of the plague in Athens, from which 5,000 fighting men and many more civilians lost their lives.
In the third year of the war, the Athenians attacked Potidaia and their opponents attacked Plataea, while they also carried the war to western Greece, with the Amvrakites as allies. The Athenians, however, thanks to their naval superiority, twice defeated the Peloponnesian fleet in naval battles in the Corinthian.
Although the Athenians were victorious until then, they suffered this year (429 BC) the catalytic loss that probably cost them the loss of the war, the loss of Pericles. The best of its leaders, at that time, succumbed to the epidemic disease, leaving an unfilled void. After his death and until the signing of the peace of Nikias (421 BC), the city was ruled by a series of men, with the most important representative being Cleon.
Cleon was a typical example of a demagogue of the time. The great success of the capture of Pylos and Sphakteria, in 425 BC. and the capture of 291 Spartans was advertised by him as his own work, when in reality it was the work of the worthy general Demosthenes. The demagogue was killed in the battle of Amphipolis. In the same battle, however, the brave Spartan opponent of Brasidas was also killed.
The unstable peace
The signing of the Peace of Nicaea (421 BC) did not clarify the landscape in Greek political affairs. It was essentially a long-term truce, signed in order to provide the necessary respite to the belligerents, to later continue the war. After 10 years of conflict, neither camp had suffered an irreparable defeat.
The Peloponnesian and Boeotian allies of the Spartans, for their part, were not at all pleased with its conclusion. Their primary objective, the neutralization of Athens, had not been achieved. In fact, the Corinthians, great competitors in the commercial field of the Athenians, did not hesitate to set up a new network of alliances of their own, in which the Argives, the fanatical enemies of the Spartans, also joined.
This movement of the Corinthians was carried out as a measure of pressure on Sparta, to circumvent the Nicaean peace. Naturally, the formation of the Corinthian League alarmed the Spartans, who responded with a separate agreement with the Boeotians. The Athenians, for their part, on the initiative of the rising star of their political scene, Alcibiades, concluded an alliance with the Argives, the Helians and the Mantineans, an alliance which by definition was directed against Sparta.
A consequence of this agreement was for the Corinthians to return to the Spartan chariot. So everything was ready for the resumption of war, all that was needed was the spark that would ignite its fire. It is rather absurd to blame the resumption of conflicts on the ambition of one man, Alcibiades. Regardless of his ambitions and desires, the fact was that fertile ground was found for their cultivation.
In the summer of 419 BC the allies of the Athenians, the Argives, campaigned against Epidaurus. The Spartans could not remain unmoved by this threat. They reinforced the city's guard with 300 of their men, but tried not to disturb, as much as possible, their relations with Athens.
And the sober Athenians, however, tried to avoid the re-explosion of a generalized war. As a first measure, they removed the generalship from the pro-war Alcibiades and assigned power to the generals Nikias, Lachitas and Nicostratus. The Spartans, however, could not in any way allow the formation of a strong coalition against them, within the Peloponnese.
War in the Peloponnese
On the occasion of the Argive attack on Epidaurus, they gathered the forces of the Peloponnesian Alliance and campaigned against their Argive, Ilian and Mantinean opponents. Led by the king of Sparta, Agi, a mighty army was formed.
It included about 4,200 Lacedaemonians, 5,000 Boeotians, 2,000 Corinthians and 1,500 Arcadian hoplites. The forces of the cities of Fleiountos, Megara, Epidaurus, Sikyona and Pelline joined her. A total of 20,000 hoplites and at least as many small men and a few horsemen were gathered. On the other hand, the Argives and their allies managed to gather 16,000 hoplites and a similar number of small soldiers.
As the two armies maneuvered to occupy advantageous ground, the Peloponnesian army managed to encircle the opponent. Agis could then achieve an overwhelming victory. He did not pursue it, however, trying to avoid the definitive rupture. He even proceeded to conclude a four-month truce with the Argives. The latter, however, with the promptings of Alcibiades, ambassador of Athens at the time, decided to continue the war against Sparta.
When Athenian reinforcements arrived in Argos (1,000 infantry and 300 cavalry), the Argives were persuaded to denounce the truce and prepared to attack the enemies. The first target of the Argives and their allies was the small town of Arcadian Orchomenos. Polichni was soon captured and the allies, after this success, headed towards the loyal ally of the Spartans, Tegea. However, the Helios disagreed with the specific plan of operations and withdrew from the coalition of the Argives.
In the meantime the Spartans had mobilized their forces and together with their Tegean allies moved against the wars. The Argives and their allies had taken positions on the slopes of Mount Alysios, astride the road that connected the Arcadian Orchomenos with their city. The position was naturally a fortress and the Spartans did not even dare to attack their enemies stationed there.
In an attempt to lure his opponents to fight on the plain of Mantineia, the Spartan king Agis ordered his men to divert the river Opheus so that the cultivated lands of Mantineia would be flooded.
He hoped that in this way the Mantineans, seeing their property destroyed, would force their Argive allies to come down to the plain and fight.
The Catalytic Battle
The next day the Argives and their allies descended on the plain. Their army numbered about 7,500 men. Of these about 3,000 were Mantineans, Arcadians, Cleonians and Orneatians, 3,000 were Argives and 1,300 Athenians. Read more at the source