Hiram Ulysses Grant, later Ulysses S. Grant, was born into a quickly changing world. America was constantly marching westward, first to Ohio, then Illinois, then the Plains, the Rockies, and the West Coast. Manifest destiny was the rule of the land.

Over the entire country, the issue of slavery loomed large. Politicians were constantly balancing the needs of the slave states against those of the free states. Two years before Grant was born, the Compromise of 1820 had admitted Missouri into the Union as a slave state. It also stated that slavery would not be allowed in any state formed north of Missouri's southern border–which worked as a fine solution until the Mexican War brought even more territory into the country. Therefore, in 1850, when California–which straddled the arbitrary line that defined slave and free–asked to enter the Union, another debate ensued. Finally, the Compromise of 1850 allowed California to enter as a free state and determined that the other territories gained during the war could choose whether to enter as free or slave. Next, the Kansas- Nebraska Act extended the 1850 compromise to all the territories, setting off a bloody battle to determine the status of Kansas as slave or free.

None of the changes and compromises made much difference in the larger debate, as the agrarian slave-holding South continued to feel alienated by the industrialized free North. The final straw came in November 1860, when abolitionist-leaning Abraham Lincoln was elected the sixteenth President. Secession of the Southern states became the talk of the nation.

On December 20, 1860, South Carolina was the first state to secede from the Union. Other states followed within a few months. Then, when a dispute over ownership of the fort in Charleston harbor exploded in April 1861, the Confederate States of America declared war on the United States of America. More states seceded from the Union and the battles lines were drawn: Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Tennessee, Mississippi, Louisiana, Arkansas, and Texas to the South and the other twenty-three states to the North.

For the next four years, brother fought brother and father fought son, especially in the bitterly divided border states. The Southern generals, particularly Robert E. Lee, Simon B. Buckner, and James Longstreet among many others, quickly proved themselves far more capable than their Northern counterparts. In fact, though the North vastly outnumbered the South in terms of troops and resources, the early years of the war belonged to the South. The North shifted from general to general in search of a solid leader, and Grant finally proved himself the man.

Upon taking command of the Union troops, Grant began to heavily exploit the Northern advantage in resources, turning the war into a bloody but effective battle of attrition. Grant thereby reinvigorated the Northern war effort and saw it through to its finish. Meanwhile, on January 1, 1863, Lincoln issued the Emancipation Proclamation, freeing the four million slaves still held in the South and radically reshaping the war from one of Union to one of freedom and liberation. It took two more years before Lee surrendered to Grant at Appomattox in Virginia. The American Civil War was finally over, but it had claimed 600,000 lives–more than in all other American wars combined.

Upon Lincoln's assassination in 1865 soon after the war ended, the next President, Andrew Johnson, began a program of Reconstruction that pleased no one. Johnson stationed federal troops in the South, and Congress passed three amendments to the Constitution: the Thirteenth Amendment abolished slavery in the entirety of the United States, the Fourteenth Amendment granted due process and equal protection to all citizens, and the Fifteenth Amendment gave everyman the right to vote regardless of his "race, color, or previous condition of servitude."

The time in which Grant became President was between two eras, marking the end of Reconstruction and the beginning of the Gilded Age, when American business excesses became famous and the transcontinental railroad linked the country coast to coast. Grant's administration became permanently linked to the horrible corruption and cheating that marked American politics of the day, and ultimately inspired reform under Presidents Rutherford B. Hayes and James A. Garfield.