Italy
The Interregnum
Frederick was succeeded by his son Conrad. Pope Innocent left Conrad more or less alone, and the Lombard League, formed to combat Frederick, dissolved.
Conrad IV died in 1254. A few years of struggle ensued, but gradually Frederick's illegitimate son Manfred claimed the throne, being crowned King of Sicily in 1258.
In 1261 Urban IV became pope. He was French and took up again the papal goal of destroying that "race of vipers." He invited Charles of Anjou, brother to the king of France, to claim the Sicilian throne. Essentially, if Charles could destroy Manfred, he could have his own kingdom.
Charles invaded in 1265. He defeated and killed Manfred the following year. Conrad's son Conradin, now of age, invaded from Germany in 1268, but he was defeated, captured and executed. So ended the House of Hohenstaufen.
Several decades of war resulted in significant consquences. For one thing, the rival camps of pope and emperor were now deeply ingrained in Italian political life. The papal faction was known as the Guelfs, taking their name from the German family of the Welfs, who were once the chief rivals of the Hohenstaufen. The imperial faction was known as the Ghibellines.
The destruction of the Hohenstaufen resulted in a perod of more than twenty years during which there was essentially no emperor. This is known in imperial history as the Great Interregnum.
The conflict also pretty well assured that no one would rule Italy, but that it would instead remain a place of competing powers. This central fact conditions everything political during the period of our course.