It is important to set the historical record straight: The overwhelming majority of Palestinian refugees left what was then the newly-established State of Israel on their own accord due to structural weaknesses within Palestinian society and their leadership.
The pressure of wartime conditions triggered the collapse of what was already a fragile Palestinian society, particularly when Palestinian leaders chose to oppose the Jewish state by a show of arms rather than by accepting a UN plan for their own state. Those events set the stage for the forceful expulsion of countless other Palestinian Arabs from Jewish-held areas. That military necessity resulted after seven Arab armies invaded western Palestine with the goal of exterminating the newly born State of Israel.
On their own accord, an estimated 600,000 Palestinian Arabs fled a war zone, which their leaders had created. An estimated 250,000 to 300,000 of those refugees in 1948 left even before their homes became part of a war zone.
The human tragedy of being uprooted notwithstanding, Palestinian refugees were neither hapless targets nor innocent bystanders. The first stage of the 1948 war was a fierce interethnic or anti-Zionist civil war in which Palestinians were the aggressors and the initiators; the second half was an all-out war involving regular armies, whose participation the Palestinians engineered. The violent path that Palestinians chose and the ensuing fear, disorientation, and economic deprivation of war led to their own collective undoing.