Seriously, I cannot get over it unless there is some religious reason, because elsewise, the garrison did not number greatly, and even if it was of great number to pour out if the Hellenic somehow magically ambushed them in order to hit the rearguard, well, the same thing it made the Akropolis good for defense makes it bad for sallies, that not many numbers are needed to hold the path, that would go both ways, so either way, the garrison was to be trapped, so once again, why was it left at all? Even if they were priests or whatever, I just... can't understand it. Please help me understand
Herodotos is our only source for this story. He tells us that a few Athenians decided to stay behind on the Akropolis because of their alternative interpretation of the oracle that the Athenians had been given at Delphi in response to their urgent request for divine guidance. The god advised them as follows:
Vainly does Pallas strive to appease great Zeus of Olympos;
Words of entreaty are vain, and so too cunning counsels of wisdom.
Nevertheless I will speak to you again of strength adamantine.
All will be taken and lost that the sacred border of Kekrops
Holds in keeping today, and the dales divine of Kithairon;
Yet a wood-built wall will by Zeus all-seeing be granted
To the Trito-born, a stronghold for you and your children.
Await not the host of horse and foot coming from Asia,
Nor be still, but turn your back and withdraw from the foe.
Truly a day will come when you will meet him face to face.
Divine Salamis, you will bring death to women's sons
When the corn is scattered, or the harvest gathered in.
-- Hdt. 7.141.3-4
The Athenians took the "wooden wall" in the oracle to be a reference to their fleet, citing the reference to Salamis as a prediction of where they would do battle. However, some argued instead that the "wooden wall" was the old thorn hedge that used to ring the Akropolis. They therefore assumed that the Akropolis would be the Athenians' stronghold, and that its wall would be impregnable.
When the Persians actually invaded Attika, the Athenians mostly evacuated their people to Salamis and to Troizen across the Saronic Gulf. However, a few men stayed behind on the Akropolis. They blocked off the entry to the Akropolis with planks and doors, believing that they were creating the impenetrable wooden wall (Hdt. 8.51.2). The Persians soon proved them wrong, however, by setting fire to the barricade, climbing the Akropolis, and murdering everyone inside.
In short, there was certainly no military reason for the occupation of the Akropolis. If Herodotos is right, it was done in defiance of Athenian strategy, rather than as an element of it. The reason Herodotos offers is religious, but we might also speculate that the men who stayed behind were those who refused to abandon their homes to the Persians without a fight, or perhaps vainly hoped to compel the Athenians, Spartans and other Greeks to rescue them once the Persians laid siege to their position.