Upon his father's death Conrad IV. was acknowledged by many as king in Germany, but in 1251 he went to Italy, where he was fully occupied in fighting against the enemies of his house until his death in May 1254. The struggle to maintain the position of the Hohenstaufen in Italy was continued after this event; but in October 1268, by the execution of Conrad's son Conradin, the family became extinct.
After Conrad's death William of Holland received a certain allegiance, especially in the north of the country, and was recognized by the Rhenish cities which had just formed a league for mutual protection, a league which for a short time gave promise of great strength and usefulness. In January 1256, however, William was killed, and in the following year there was a double election for the German crown, Alphonso X., king of Castile, a grandson of Philip of Swabia, and Richard, earl of Cornwall, brother of the English king Henry III., being each chosen by parties of electors. Richard was crowned in May 1257, but the majority of his subjects were probably ignorant of his very name; Alphonso did not even visit the country over which he claimed to rule.
During the reign of Frederick II. Prussia was conquered for Christianity and civilization by the knights of the Teutonic Order, who here built up the state which was later, in association with Brandenburg, deeply to influence the course of history. This work was begun in 1230. Knights eager to win fame by engaging in the war against the heathen Prussians flocked hither from all lands; towns, Königsberg, Thorn, Kulm and others, were founded; and in alliance with the Brothers of the Sword, the order was soon pressing farther eastwards. Courland and Livonia were brought into subjection, and into these lands also Christian institutions were introduced and German settlers brought the arts of peace.
The age of the Hohenstaufen emperors is, in many respects, the most interesting in the medieval history of Germany. It was a period of great men and great ideas, of dramatic contrasts of character and opinion--on the one side a broad humanitarianism combined with a gay enjoyment of the world, on the other side an almost superhuman spirituality which sought its ideal in the rejection of all that the world could give. It saw the new-birth of poetry and of art; it witnessed the rise of the friars. The contest between Empire and Papacy was more than a mere struggle for supremacy between two world-powers; it was a war to the death between two fundamentally opposite conceptions of life, which in many respects anticipated and prepared the way for the Renaissance and the Reformation. The emperor Frederick II. himself stands out as the type of the one tendency; Innocent III., Francis of Assisi and Dominic, in their various degrees, are types of the other. Frederick himself, of course, was Italian rather than German, akin to the despots of the Renaissance in his many-sided culture, his tolerant scepticism and his policy of "cruelty well applied." The culture of which he was the supreme representative, that of Italy and of Provence, took a more serious shade when it penetrated into Germany. The German _Minnesinger_ and romance-writers, whose golden age corresponded with that of the Hohenstaufen, were not content only to sing the joy of life or the chivalrous virtues of courage, courtesy and reverence for women; they in some sort anticipated the underlying ideas of the Reformation by championing the claims of the German nation against the papal monarchy and pure religion, as they conceived it, against the arrogance and corruption of the clergy. In them the medieval lay point of view became articulate, finding perhaps its most remarkable expression in the ideas of religious toleration proclaimed by Walther von der Vogelweide and Wolfram von Eschenbach. In Germany, as elsewhere, the victory of the Papacy was the victory of obscurantism. German culture, after a short revival, perished once more amid the smoke of the fires kindled by Conrad of Marburg and his fellow inquisitors.