 He plotted with Henry to assassinate Otto in Easter 941 in Quedlinburg, but they were discovered and put in captivity in Ingelheim, being released and pardoned only after doing penance at Christmas of that year.Frederick refused to accompany Otto to Italy in 951.He participated in another rebellion with Liudolf, Duke of Swabia, and Conrad, Duke of Lorraine, luring the king to Mainz in 953.