Conrad IV (25 April 1228 – 21 May 1254) was king of Jerusalem (as Conrad II; 1228–1254), of Germany (1237–1254), and of Sicily (as Conrad I; 1250–1254).

Biography

He was a son of the Hohenstaufen Emperor Frederick II and the queen regnant of Jerusalem, Yolanda. Born in Andria, Conrad was the second but only surviving son of Frederick and Yolanda, who died while bearing him. Conrad lived in Italy until 1235, when he first visited Germany. During this period his kingdom of Jerusalem, ruled by his father as regent through proxies, was racked by the War of the Lombards until Conrad declared his majority and his father's regency lost its validity.

When Frederick II deposed his eldest son, Conrad's rebellious older brother Henry, in 1237 had Conrad elected King of the Romans in diet in Vienna. This title presumed a future as Emperor of the Holy Roman Empire. Archbishop Siegfried III of Mainz acted as German regent until 1242, when Frederick chose Henry Raspe, Landgrave of Thuringia, and Wenceslaus I of Bohemia, to assume this function. Conrad intervened directly in German politics from around 1240.

However, when Pope Innocent IV imposed a papal ban on Frederick in 1245 and declared Conrad deposed, Henry Raspe supported the pope and was in turn elected as anti-king of Germany on 22 May 1246. Henry Raspe defeated Conrad in the battle of Nidda in August 1246, but died several months later. He was succeeded as anti-king by William of Holland.

Also in 1246, Conrad married Elisabeth of Bavaria, a daughter of Otto II Wittelsbach, Duke of Bavaria. They had a son, Conradin, in 1252. In 1250 Conrad settled momentarily the situation in Germany by defeating William of Holland and his Rhenish allies.

When Frederick II died in the same year, he passed Sicily and Germany, as well as the title of Jerusalem, to Conrad, but the struggle with the pope continued. Having been defeated by William in 1251, Conrad decided to invade Italy in 1251 in the hope to regain the rich reign of his father, and where his brother Manfred acted as vicar.
In January 1252 he invaded Apulia with a Venetian fleet and successfully managed to restrain Manfred and to exercise control of the country. In October 1253 his troops conquered Naples.

Conrad was however not able to subdue the pope's supporters, and the pope in turn offered Sicily to Edmund Crouchback, son of Henry III of England (1253). Conrad was excommunicated in 1254, but died of a malaria in the same year at Lavello in Basilicata. Manfred first, and later his infant son Conradin, continued the struggle with the Papacy, although unsuccessfully.

Conrad's widow Elisabeth married second Meinhard II, Count of Tirol, who in 1286 became Duke of Carinthia.

With Conrad's death in 1254 began the "Interregnum", during which no ruler managed to gain undisputed control of Germany. It would only be ended with the election of Rudolph of Habsburg as King of the Romans in 1273.