The 6th Michigan was organized in 1862, and along with the 5th.and 7th Michigan Cavalry regiments, formed the Michigan Cavalry Brigade. Later, the 1st. Michigan Cavalry was added to the brigade, which saw its first major action during Lee's invasion of Pennsylvania in the summer of 1863. In late June of that year, the Michigan Brigade, including the 6th, was placed under the command of General George Custer. Under Custer's leadership, the Michigan cavalrymen distinguished themselves in combat. They saw heavy fighting at Hanover and Hunterstown, and then on July 3rd, took part in a crucial engagement against Lee's cavalry just to the east of Gettysburg. In the course of these actions, the Michigan horse soldiers demonstrated not only their own courage and ability, but also the effectiveness of superior weapons, as many of them were armed with the magazine-fed Spencer rifles and carbines.