During his studies, he organized a self-defense group of Jewish students to counter harassment by anti-Semites on campus. He graduated in 1935, but never practiced law. At this time he became a disciple of Vladimir "Ze'ev" Jabotinsky, the founder of the nationalist Revisionist Zionism movement and its youth wing, Betar. His rise within Betar was rapid: at 22, he shared the dais with his mentor at the Betar World Congress in Kraków. The pre-war Polish government actively supported Zionist youth and paramilitary movements. Begin's leadership qualities were quickly recognised. In 1937 he was the active head of Betar in Czechoslovakia and became head of the largest branch, that of Poland. As head of Betar's Polish branch, Begin traveled among regional branches to encourage supporters and recruit new members. To save money, he stayed at the homes of Betar members. During one such visit, he met his future wife Aliza Arnold, who was the daughter of his host. The couple married on 29 May 1939. They had three children: Binyamin, Leah and Hassia.