The main reason why Lincoln took such a generous approach toward the South is because he knew that punishing them further after the war would just increase bitterness, and make it impossible for the Union to ever "heal". <span />
It depends on what you take to be the beginning and what the end. It lasted two years if you understand it as from the time it was revealed to the time Nixon resigned. It lasted 5 years if you take it from the time Nixon began doing it to the time he resigned.
