Hatto II was the Archbishop of Mainz, having previously been Abbot of Fulda. He died in 970. He was not the awful villain that legend was to turn him into. The legend in question is first referred to in the 14th Century.
It is said that when people were hungry, he shut them in a barn to which he set fire. Then he was told there was a throng of rats coming, which alarmed him. He looked out of the window and a sea of rats was making its way across the countryside. The archbishop fled to a tower in the river, hoping that there he would be safe. He wasn't. In came the rats. Yum! Yum!
In fact, this is a legend which is applied to a number of people in European lore. The reason it was applied to Hatto was because of the proximity of a tower which had originally been called the Muusthurm (arsenal), but had been corrupted in local speech to the Mausethurm (mouse tower).
As I said, much the same legend exists elsewhere in Europe. One of the characters to whom it was attributed was "King Popiel of Poland". This may have been one of the two Dukes of the West Slavs so called. It was said that this felonious monarch poisoned those who grumbled against him, but their bodies engendered large numbers of mice, who viewed Popiel with luncheon in mind. The hapless king first tried to protect himself by surrounding himself with fire, but the doughty rodents were unfazed by this. Then he fled to a castle in the sea, where the mice finally caught up with him. They enjoyed their prandial refreshment.
