In response to numerous Arab attacks on Jewish communities , the Haganah , a Jewish paramilitary organisation , was formed on 15 June 1920 to defend Jewish residents . Tensions led to widespread violent disturbances on several occasions , notably in 1921 ( see Jaffa riots ) , 1929 ( primarily violent attacks by Arabs on Jews — see 1929 Hebron massacre ) and 1936 – 1939 . Beginning in 1936 , Jewish groups such as Etzel ( Irgun ) and Lehi ( Stern Gang ) conducted campaigns of violence against British military and Arab targets
1929 Hebron massacre
1929 Hebron massacre
Mandatory Palestine