Before the civil war, growing populations were changing the balance of?

In 1877, soon after retiring as president of the United States, Ulysses S. Grant, embarked with his wife on a two-year tour of the world. At almost every location, he was greeted as a hero. In England, the son of the Duke of Wellington, whose father had vanquished Napoleon, greeted Grant as a military genius, the primary architect of Union victory in the American Civil War.