Some of them turned very violent, and some of them turned out peaceful.
Ulysses S. Grant was president from 1869-1877
The Han Dynasty changed a few notable policies that were established.
1) The Qin Dynasty banned Confucianism (belief that people are naturally good) and rather focused on Legalism, but the Han dynasty lifted the ban and allowed it to be practiced once again. The Han Dynasty used Confucianism as a model by which to govern.
2) The Han Dynasty reversed the autocratic policies of the Qin Dynasty. The Qin Dynasty was ruled by a single emperor (which is an autocracy) but the Han Dynasty allowed several leaders to rule and have power rather than one man.
I'm sure there are more, but these ones should do. Hope this helps! :)
The single event that most tarnished Ford's presidency was his decision to pardon Nixon. He also, however, presided over the worst US economy since the Great Depression.