A mandate is not ownership... just so you know.. the Brits did not have the authority to give the jews any land in Palestine.
Actually, that's exactly what it means. The British had the complete authority to parcel that land as it wished because the previous owners (the Ottoman Empire) ceded it automatically with its dissolution in losing World War I.
And again, you make it sound like the entire region was already developed and settled by Arabs. The hundreds of thousands of Jews that migrated into the Mandate from 1918-1948 didn't displace a single Palestinian. And the vacant land that the Jews settled could become Israel because Jews were a majority on those lands. The British and the United Nations merely recognized that fact.
i don't know what they taught you at school, but when more than 300 civillians are killed, it is a massacre.
The number is anywhere between 90-150. And a massacre is not defined by the death count but by how the deaths occurred. If a Canadian army laid siege to Manhattan Island and 20 million starved because American forces wouldn't surrender, that would not be a massacre.
Besides, the number of civilian casualties in Deir Yassin was not abnormal when one takes into account the fact that house to house fighting went on in the village for days.
Also, it would have been unusual for the Israeli unit to plan a massacre and then give Deir Yassin's civilians a warning to get out of the village before it was attacked, which is exactly what they did.
You can't say "they left willingly" and left the land vacant.
Israel didn't even control Gaza before, during or after the 1948 war. And when Israel did come into control of Gaza during the 1967 war, there was no large scale movement of Palestinians out of the strip. The Gaza Strip remains one of the most densely populated pieces of land on the planet with over 1 million Palestinians.
Palestinians didn't flee the Gaza Strip en masse during the war only to have Jewish settlers strut into their houses or something. After the war, Jewish settlers voluntarily entered Gaza and settled on vacant land.
Some sources originally reported a death toll of around 254, but that number has recently been shown to be a contemporary exaggeration that was disseminated for a variety of political reasons.
The exaggerated death toll and stories were disseminated by both the Israeli and Arab militias in the immediate aftermath of the battle. The Israelis wanted to scare Palestinian civilians into fleeing. The Arabs hoped the propaganda would embitter and embolden more Palestinians to join the fight.
Yet the attack was carried out by underground paramilitary dissidents who were not acting on behalf of the Haganah.
Regardless of how we describe the Israeli militia that attacked Deir Yassin, the attack occurred because Arab militias were using Deir Yassin to attack Israeli targets.

