[2] After foiling an Athenian attempt to capture Megara,[3] Brasidas marched his army through Thessaly and linked up with Perdiccas II of Macedon, one of Sparta's northern allies.

[6] In the winter of 424–423, around the same time as the Battle of Delium, Brasidas besieged Amphipolis, an Athenian colony in Thrace on the Strymon river.

[10] Thucydides arrived at the nearby port of Eion on the same day the city surrendered, and defended it with help from those who had left Amphipolis.

The Athenians were afraid that their other allies would quickly capitulate, as the Amphipolitans had, if Brasidas offered them favourable terms of peace.

When the armistice ended in 422, Cleon arrived in Thrace with a force of 30 ships, 1,200 hoplites, and 300 cavalry, along with many other troops from Athens' allies.

In an excerpt of Brasidas' brief pre-battle speech, he specially addressed the allied Lacedaemonian forces, whom he assigned under Clearidas leadership, while for himself he handpicked a hundred and fifty hoplites; he said: "..bear in mind that the three virtues of a good soldier are zeal in battle, sense of honor and obedience to the leaders..and I will reveal that I will conduct myself in action following the advice I give to my comrades.

They also made him the city's founder and dedicated it to him, pulling down the buildings which Hagnon the Athenian had erected and destroying any memorials which might have remained to future time of his foundation.

[16] After the battle, neither the Athenians nor the Spartans wanted to continue the war (Cleon being the most hawkish member from Athens), and the Peace of Nicias was signed in 421 BC.

Thucydides was exiled for his failure to protect Amphipolis, thus ending the period of the war in which he directly participated.