Louis the German
In 871, a Saxon vassal of Henry's was blinded on the orders of Louis the German, which prompted Louis the Younger and Charles to temporarily cut off relations with their father in solidarity with Henry. Nothing is known of Henry's reaction to this incident. It has been suggested that Louis the German took advantage of his sons' insubordination to remove Henry from power in Saxony and replace him with Duke Bruno (brother of the aforementioned Otto, who probably married Henry's daughter).