Clement took over the papacy with the support of the German King Henry III; Pope Clement in turn made Henry the Holy Roman Emperor. This did not please the people, but both were allowed to maintain their positions.

Here's a great tidbit, straight from Wikipedia:

A recent toxicologic examination of his remains confirmed centuries old rumors that the Pope had been poisoned with lead sugar. It is, however, not clear whether he was assassinated or not, as lead sugar in those times was often used as a cure for venereal diseases.