During the 1948 Palestine war, more than 700,000 Palestinian Arabs – about half of Mandatory Palestine's predominantly Arab population – were expelled or fled from their homes. Expulsions and attacks against Palestinians were carried out by the Zionist paramilitaries Haganah, Irgun, and Lehi, which merged to become the Israel Defense Forces after the establishment of Israel part way through the war. The expulsion and flight was a central component of the fracturing, dispossession, and displacement of Palestinian society, known as the Nakba. Dozens of massacres targeting Arabs were conducted by Israeli military forces and between 400 and 600 Palestinian villages were destroyed. Village wells were poisoned in a biological warfare programme, properties were looted to prevent Palestinian refugees from returning, and some sites were renamed.