 Complete the following phrase:  The return of several hard-line Palestinian Arab nationalists, under the emerging leadership of Haj Amin al-Husseini, from Damascus to Mandatory Palestine marked the beginning of Palestinian Arab nationalist struggle towards establishment of a national home for Arabs of Palestine. Amin al-Husseini, the architect of the Palestinian Arab national movement, immediately marked Jewish national movement and Jewish immigration to Palestine as the sole enemy to his cause, initiating large-scale riots against the Jews as early as 1920 in Jerusalem and in 1921 in Jaffa. Among the results of the violence was the establishment of the Jewish paramilitary force Haganah. In 1929, a series of violent anti-Jewish riots was initiated by the Arab leadership. The riots resulted in massive Jewish casualties in 