Ivan IV., surnamed The Terrible, grandson of the preceding, assumed the sovereignty at 14, had himself crowned in 1545, and took the title of Czar; his first great ambition was to destroy the Tartar power, which he did at Kasan and Astrakhan, receiving homage thereafter from almost all the Tartar chiefs; on the death of his wife in 1563 he lost all self-restraint, and by the ferocity of his wars provoked hostility which the Pope, who had been appealed to, interposed to appease; in a fit of passion he killed his eldest son, whom he loved, remorse for which embittered his last days and hastened his end (1530‒1584).
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Ivan III. * Ivanhoe