One thing I've read (and don't remember from my childhood) is that the Swedish UN-appointed mediator for Palestine, Count Folke Bernadotte, was assassinated - among others - on September 17, 1948.
From what little I read, some are of the opinion that the Palestianian version of what happened at Deir Yassin did more harm to the Palestianian cause than good.
I like to blame the British for the whole Israel/Palestine mess. In the same way and for the same reason as the India/Pakistan mess.