At the beginning of the Civil War, the Union Army incorporated most State militia units from the States adhering to the Union, mainly because they were offered for federal service by their States in response to President Abraham Lincoln's call for volunteers to put down the rebellion of the Confederate States. If the generals of these units did not receive appointments by the President of the United States and confirmation by the United States Senate and come into federal service with their units, new Union Army generals were appointed and confirmed for the Union Army brigades or divisions in which the units were placed. States often retained or further recruited some militia units for local defense but these units, including any generals, saw little, if any, combat in the Civil War as State units. State militia units remaining under State control did not leave their States for service elsewhere and few battles or lesser actions were fought in the Northern States. The battles of South Mountain, Antietam, Gettysburg and Monocacy were among the more notable exceptions.