The popes still tried to stir up the Christians of the West for the recovery of the Holy Land; and there were crusading attempts from time to time, although without much effect. One of these crusades was undertaken in 1228 by Frederick II., an emperor who was all his life engaged in struggles against one pope after another. Frederick had taken the cross when he was very young; but when once any one had done so, the popes thought that they were entitled to call on him to fulfil his promise at any time they pleased, no matter what other business he might have on his hands. He was expected to set off on a crusade whenever the pope might bid him, although it might be ruinous to him to be called away from his own affairs at that time. In this way, then, the popes had got a hold on Frederick, and when he answered their summons by saying that his affairs at home would not just then allow him to go on a crusade, they treated this excuse as if he had refused altogether to go; they held him up to the world as a faithless man, and threatened to put his lands under an interdict,[81] and to take away his crown. And when at last Frederick found himself able to go to the Holy Land, the pope and his friends set themselves against him with all their might, saying that he was not hearty in the cause, and even that he was not a Christian at all. So that, although Frederick made a treaty with the Mahometans by which a great deal was gained for the Christians, it came to little or nothing, because the popes would not confirm it. [81] See page 219. I need not say much more about Frederick II. There was very much in him that we cannot approve of or excuse; but he met with hard usage from the popes, and after his death (A.D. 1250) they pursued his family with constant hatred, until the last heir, a spirited young prince named Conradin, who boldly attempted to recover the dominions of his family in Southern Italy, was made prisoner and executed at Naples in 1268. PART II.