In response to President Lincoln's call for 75,000 volunteers, it was organized at Galena, Illinois.

One member of the regiment, Wilbur Fisk Crummer, wrote a book about experiences titled With Grant at Donelson, Shiloh and Vicksburg.

[1] Crummer's service ended in July 1863 when he was wounded and the book does not cover what happened to the 45th after that time.

Crummer later wrote that at the Battle of Jackson, Mississippi, Confederate Minié balls were fired into beehives, and angry bees caused several Union companies to retreat.

In Dec 1863, the 45th was located at Black River, MS The regiment was mustered out on July 12, 1865 at Louisville, KY.