After Rabbi Mordechai's sudden death in November 1949, Rokeach raised his half-brother's year-old son, Yissachar Dov, and groomed him to succeed him as Belzer Rebbe.

His strict regime of seclusion, deprivation, and asceticism caused him to become seriously weakened, whereupon his doctors recommended a complete change of locale and sent him to a spa.

Though he recuperated at the health resort of Kreniec, he still ate little, and his chronic sleep deprivation made it difficult for him to stand or walk quickly.

[2] When Rokeach's father, Rebbe Yissachar Dov, died in Belz on Friday night, 30 October 1926, his 46-year-old son accepted the mantle of leadership at the funeral held after Shabbat.

At first, he tried to limit the number of petitioners who sought his counsel and blessing to five per night, saying, "I simply can't take these tzoros (tribulations) of Klal Yisrael!"

During World War II, Belzer Hasidim both inside and outside Nazi-occupied Europe saw saving the Rebbe as their primary goal.

[2] In their most hair-raising escape attempt, the brothers were driven out of occupied Poland and into Hungary by a Hungarian counter-intelligence agent who was friendly to Jews.

Rokeach, his attendant, and Rabbi Mordechai, shorn of their distinctive beards and sidelocks, were disguised as Russian generals who had been captured at the front and were being taken to Budapest for questioning[citation needed].

After spending eight months in Hungary, the brothers boarded the Orient Express to Istanbul and finally arrived in Mandatory Palestine in February 1944.

He developed a very inclusive attitude to modern and even non-Orthodox Jews, a substantive change from his pre-war practice of associating almost exclusively with other Haredim.

Unlike some of his other Hasidic rebbe peers, who had survived the Holocaust and made a practice of acknowledging and honoring their deceased followers and recounting their own experiences, it was Rokeach's custom to never speak of the Belz Hasidim who had died during the war, particularly members of his own family.

[citation needed] On one occasion, rabbi and author Arthur Hertzberg, a descendant of Belz Hasidim, visited the rebbe and attempted to talk to him about Belz before the war: He talked willingly of [my] grandfather, remembering that ... [he] had been his teacher when he was young, but he was silent when I mentioned my mother's father and her brothers, who had been his disciples until they were murdered during the war.

This strange behavior was later explained to me by his principal assistant: the rebbe had not once said any of the prescribed prayers (Yizkor, Kaddish) for his wife and children because those who had been killed by the Nazis for being Jews were of transcendent holiness; they were beyond our comprehension.