During the Civil War, Jefferson Davis allows an invasion of South America, conquering what is modern day Mexico, Peru, Argentina and Brazil in one of the most successful military campaigns of the South. Due to the thinning of the Confederate Army during the campaign, Abraham Lincoln wins the war in only one year and six months. This victory and the passing of what are the modern-day 13th-15th Amendments before his second begins, and in return gaining all of South America from the countries that previously owned it.
Due to this divergence in history, Davis inadvertently made the U.S.A. the strongest country in the world much earlier, due to full control of both Americas in only ten years. With the annexation of Canada and Alaska by the end of Lincoln's second term, the U.S. became the greatest power, due to the ability to trade Japanese spices to New York and out to London in under a month. This also caused unrest in Europe, due to the loss of several colonies, and leading to an intense political climate.