In April of 1862 General Ulysses S. Grant of the Union army led around 40,000 troops south trying to reach Corinth, Mississippi, but ended up camping at Pittsburg Landing. The Yanks were waiting for reinforcements to come from Nashville, Tennessee. The Confederate forces led by Generals Albert S. Johnston and Pierre G.T. Beauregard launched a surprise attack on General Grant on April 7, 1862. Although they were surprised the Yankees were able to barley defeat the Rebels.
Total there were about 23,000 casualties. The Union forces quickly gained control of Corinth by late May. This was a Union victory.