Samuel McKee was born in Pittsburgh, PA in 1840, and attended the military academy in Frankfort, Kentucky.  When the civil war erupted, he returned to Pennsylvania, where applied to the authorities for a civilian appointment to the Regular army. Hearing no response from the authorities, he joined the 62nd Pennsylvania - while his brother accepted a commission in the 13th PA Reserves (the "Bucktails").

After the debacle of First Bull Run, the Regular officers corps was replenished, and McKee was finally granted a Regular Army commission in 1861, joining Company. I, 2nd U.S. Infantry as 2nd Lt. at the age of 21. By the battle of Gaines' Mills, McKee was promoted to 1st Lt. and had gained the attention of the senior officers of the 2nd Infantry.  McKee's valor in combat was undeniable. He was wounded in the leg at Gaine's Mills, led his company at Second Bull Run and at Antietam, where he was again wounded. By the Fredericksburg Campaign of December 1862, McKee was promoted to Captain, and took command of Co. K.

At Chancellorsville, Capt. McKee briefly took command of the 2nd Infantry after Capt. Salem Marsh was killed in action. Two months later, McKee was wounded a third time at Gettysburg, and took command of the 2nd Infantry after Major Arthur Lee was killed on July 3rd. With the rest of the 2nd Infanty, Capt. McKee would spend the next few months recovering after the harrowing ordeal of Gettysburg.

By early 1864, the 2nd Infantry had re-deployed in northern Virginia to help secure the area against enemy partisans, including Mosby's raiders.  Insurgent activity had subsided in large part by February, in part due to the presence of a larger force of Federal troops, including several small Regular regiments.  In April 1864, Capt. McKee was killed by enemy guerillas on a wooded country lane in the village of Greenwich, VA.  Capt. McKee and three of his Lieutenants were visiting acquaintances several miles north of the regiment's location at Catlett's Station. Near their destination, they were ambushed by two local residents who were members of the 4th VA Cavalry.

Capt. McKee's death was an irreplaceable loss for the Regular Army, and came just weeks before the Wilderness - one of the last major engagements the 2nd Infantry would undertake.