Rabbi Betzalel Wilshansky was a Torah scholar and educator who led a yeshiva, and who corresponded with the Rebbe over many years on scholarly and educational matters. No reliable published biography is available; the summary below is drawn from the letters themselves.
The yeshiva. The Rebbe urged him to increase the number of students and the effort invested in education (IK 1778), to make the yeshiva a center for Torah and Yiddishkeit in its surroundings (IK 3000), and encouraged its growth (IK 3103). He wrote on personal responsibility in decision-making and action for the institution (IK 3744), on planning ahead for Kislev and the responsibility to spread Chassidus (IK 5902), and on the attitude Chabad men should take toward organizing Nshei uBnos Chabad (IK 2888).
Scholarly questions. Other letters answer his questions on the order of knowledge, knower and known in Tanya (IK 437); the berachah when switching a Sefer Torah during the reading (IK 2650); calculating one's age through riddles and gematria (IK 2515); and the text and proper wording of Seder Yetzirah for the night of Shavuos (IK 8227).
See also: Education – Running a school; Education – Yeshiva students.