At first Sparta avoided involvement in Macedon's war with Arrhabaeus, but in 423 BC they joined an expedition which ended with retreat by the Macedonians and a brilliantly contrived escape of the Spartans.
[1] After the initial joint Illyrian and Lyncestian attack was repulsed, they pursued the Macedonians and blocked Brasidas' route at a pass, forcing his army up the surrounding hill and into Macedonia.
In return for this, and after initial reluctance, the Spartans helped Perdiccas secure his borders, by leading an assault on King Arrhabaeus, with the promise of support from the Illyrians.
After this, the Lyncestian hoplites advanced from their hill to join their cavalry and offered battle; in response to which Brasidas and Perdiccas also came down to meet them, and engaged and routed them with heavy loss; the survivors taking refuge upon the heights and there remaining disengaged.
At daybreak, Brasidas, seeing that the Macedonians had gone, and that the Illyrians and Arrhabaeus were on the point of attacking him, formed his hoplites into a square with the light troops in the centre, and prepared to retreat.
Posting his youngest soldiers to dash out where ever the Illyrians and Lyncestians should attack them, Brasidas and 300 picked men went to the rear intending to face about during the retreat and to beat off the most forward of their assailants.
The main body of the Illyrians and Lyncestians ceased to molest Brasidas and his troops once they were in open country, and left just a part of their forces behind to follow them and keep up the attacks.
The rest made off at a run after the fleeing Macedonians, killing any they caught, and went on ahead to take control of the narrow pass that lay between two hills and led into Lyncestis, knowing that Brasidas had no other line of retreat.
His men attacked and overpowered the party on the hill, enabling the main body of Peloponnesians to make their way to join them with relatively little difficulty.