Sternhartz immigrated from Uman, Ukraine to Jerusalem in 1936 and taught many students, producing Breslov leaders for coming generations.

[4] At age 18, Koenig married Esther Yehudit, the daughter of Rabbi Dovid Moshe Ehrentrau of Jerusalem.

[1] He wrote Chayei Nefesh, a book explaining the meaning of binding oneself to the tzaddik (in response to the Nefesh HaChaim by Rabbi Chaim Volozhin), which was published during his lifetime, and left many unpublished manuscripts filled with chiddushim (new Torah thoughts) on Likutey Moharan, Rebbe Nachman's major work.

[4] His collected letters, entitled Shaarei Tzaddik ("Gates to the Righteous"),[1] were published prior to Rosh Hashanah in 2012 (5773) in two volumes.

[4] Koenig died in Manchester, England on 7 July 1980 (23 Tammuz 5740), while fund-raising on behalf of the Breslov community in Safed.