1. Early Zionists knew a Jewish state would displace Arabs but had no plan to expel them as they themselves had been refugees.
2. As fighting broke out in 1947-1948, upper and middle class Arabs fled cities, causing working class Arabs to panic.
3. Subsequent defeats of Arab militias by the IDF led to widespread panic and abandonment of villages.
4. Ben Gurion later ordered some expulsions of hostile villages to secure lines of communication and prevent return of refugees. Offers were made to allow return of some refugees but rejected by Arab leaders.