18th Michigan Volunteer Infantry resulted from President Lincoln's call on July 2, 1862 for an additional 300,000 troops. Recruits came from the counties of Hillsdale, Lenawee, and Monroe. Mustered into service on August 26, 1862 , the regiment left Hillsdale, Michigan with 1,002 soldiers.

Until the regiment was mustered out on June 26, 1865, they were stations in Lexington, Kentucky, Nashville, Tennessee; and Decatur, Alabama. When the regiment returned to Jackson, Michigan on July 2, 1865 it was paid off and disbanded.

The First Michigan Regiment was created by Governor Austin Blair, April 16, 1861, in compliance with President Lincoln's requisition. Ten independent military companies formed the First Michigan Regiment and were designated at their home camps as the "Detroit Light Guard", the "Jackson Grays", the "Coldwater Cadets", the "Manchester Union Guards", the "Stuben Guard", the "Michigan Hussars", the "Burr Oak Guard", the "Ypsilanti Light Guard", the "Marshall Light Guard", and the "Hardee Cadets". Orlando P. Wilcox was appointed Colonel of the Regiment.

The Regiment was mustered into the Federal service on May 1, 1861 with a total enrollment of 798. After serving in Virginia, and participating in the battle at Manassas, Virginia, the Regiment returned to Michigan at the expiration of its three months term of enlistment and was mustered out of Federal service on August 7,1861. The Regiment was immediately reorganized into a three year term of enlistment and set out for Virginia on September 7,1861, with 960 officers and men.

The Regiment took part in the battles of Antietam, Fredericksburg, Chancellorsville, and Gettysburg. It was then engaged in active duty, with frequent contacts with Confederate forces until February of 1864, when its enlistment term expired. At that time, 212 of its members re-enlisted and was continually employed, either building fortifications or skirmishing with the Confederates until February 5, 1865, when it started on the pursuit of General Lee's retreating forces around Richmond, until the surrender of the Army of Northern Virginia at Appomattox Court House. After the surrender the Regiment was mustered out of Federal service on July 19, 1865. They returned to Jackson, Michigan July 22, 1865 where they were ceremoniously paid off and disbanded.