The war lasted almost 2 years. Although the U.S. gained about 1.2 million square miles of land as well as having the Wilmot Proviso outlaw slavery other than where it already was, nearly 13,000 Americans lost their lives and the country invested around $100 billion into the war. Slavery was becoming more of an issue. Southerners wanted to get rid of the Wilmot Proviso while many northerners wanted the abolishment of slavery. When Lincoln was elected, Southern states were convinced that he would abolish slavery. In response to this, 11 states seceded to form the Confederate states of America. When the American Civil War began, President Lincoln was not prepared to be commander in chief. Lincoln appointed many prominent politicians and ethnic leaders with little or no military training or experience to the rank of brigadier or major general. By April 1862, when the war was a year old, the volunteer Union army had grown to 637,000 men. This mass mobilization could not have taken place without a huge effort from Lincoln's appointed politicians and ethnic leaders. During the war's early stages, anti-slavery Republicans grew more demanding. They argued that slavery had brought on the war and that its survival would cause another war. Many northerners, including Lincoln, became convinced to win the war over an enemy fighting for and sustained by slavery, the North must strike at slavery. In July 1862, Lincoln instated the Emancipation Proclamation.
In the spring of 1865, Robert E. Lee surrendered the last major Confederate army to Ulysses S. Grant on April 9, 1865. The Civil War was by far the deadliest war in American history. Over 600,000 people died. The result of the Civil War left many in the South bitter toward the integration of African Americans into society. The Jim Crow Laws were created to punish African Americans legally. In May, 1945, World War II had just ended in Europe. In August, the United States drop atomic bombs on Hiroshima.