The Union Army was the land force that fought for the northern states during the American Civil War from 1861 to 1865. It was led by several key generals who played crucial roles in various battles and campaigns. Notable figures included Ulysses S. Grant, who later became the 18th President of the United States, and William Tecumseh Sherman, known for his "March to the Sea." These generals were responsible for strategizing and executing military operations against the Confederate Army. Their leadership helped secure significant victories, ultimately contributing to the preservation of the Union and the end of slavery in the United States.