In 1937, the sixth Chabad Rebbe, Rabbi Yosef Yitzchak Schneersohn, of righteous memory, traveled to Perchtoldsdorf, Austria, for health reasons. Perchtoldsdorf was a resort area which boasted fresh air and comfortable accommodations.
His son-in-law, Rabbi Menachem Mendel, joined him from Paris, where he and his wife, Rebbetzin Chaya Mushka, were living at the time. During his stay in Perchtoldsdorf, Rabbi Menachem Mendel, who would later succeed his father-in-law as leader of the Chabad movement, directed all the Chabad activities in accordance with the instructions of his father-in-law, the Rebbe.
In order to preserve his health, the doctors instructed Rabbi Yosef Yitzchak to refrain from all forms of exertion, including his habitual strenuous intellectual activity. This precluded him from following much of his standard daily routine of studying and contemplation.
So the Rebbe would at times play chess.
During one such game with his son-in-law, he realized that Rabbi Menachem Mendel, out of his deep respect for his father-in-law, was trying to lose — albeit in an unobtrusive manner.
Rabbi Yosef Yitzchak told his son-in-law, "We must play honestly..."
I heard this story from Sholom Ber Butman, a cousin of the Rebbe.
