Germany during the Crusades
Conclusion
Meanwhile, down in Sicily, Charles of Anjou proved to be extraordinarily ambitious, and he seemed determined to make Sicily finance those ambitions. In 1282 the locals had had enough, and there was a widespread revolt, known as the Sicilian Vespers. The revolt put an end to Charles' ambitions in the East (which included an attack on Byzantium—some themes remain constant!).
In short, after Frederick there were no more effective emperors. The popes achieved their goal. A couple of emperors in the 14th century tried to regain control south of the Alps, but none came anywhere near close. The Empire increasingly became restricted to Germany, and the popes found themselves enmeshed in Italian politics.
All that narrative, however, belongs to another course.