As for the Hague Convention and Geneva Convention, i think they are reffering to each country's armed forces -not civilian defenders
Well first of all the Annex to the Hague 1907 Convention - REGULATIONS RESPECTING THE LAWS AND CUSTOMS OF WAR ON LAND
SECTION I ON BELLIGERENTS CHAPTER I The Qualifications of Belligerents says:
The inhabitants of a territory which has not been occupied, who, on the approach of the enemy, spontaneously take up arms to resist the invading troops without having had time to organize themselves in accordance with Article 1, shall be regarded as belligerents if they carry arms openly and if they respect the laws and customs of war.
So civilians are allowed to take-up arms against the invading force. But only if they respect the laws of war: And in the case of crete that is:
THE GENEVA CONVENTION OF JULY 27, 1929, RELATIVE TO THE TREATMENT OF PRISONERS OF WAR.
Title 1. General provisions:
Prisoners of war are in the power of the hostile Power, but not of the individuals or corps who have captured them.
They must at all times be humanely treated and protected, particularly against acts of violence, insults and public curiosity.
Measures of reprisal against them are prohibited.
If the laws of war only applied to 'soldiers' one could then neglect to put them in uniform, claim they were civilians and then go on a rampage.... and the laws of war wouldn't be worth the paper they were written on....
The Cretan's didn't attack anyone.
They were defending their homeland against invaders.
Also consider the fact that the atrocities on Greece's mainland were well known in the island.
The fact that german armed forces was responsible for attrocities committed on mainland greece does not change the fact that the laws of war is to be honoured. As stated in the article of the geneva convention cited above, reprisals are forbidden. While we may understand the feelings of the cretans, vigilante or revenge can not be allowed. If a girl is raped and killed and the father shoots the perpetrator in court we may understand his emotions. But he is still a killer, and would be prosecuted as such. While national laws tend to take issues such as manslaughter into account, and evenen to some extent excuse the actions of the vengefull father, the laws of war at the time of world war two did no such thing. Reprisals were forbidden.