By Scott Valentine
Brigadier Gen. Joseph King Fenno Mansfield mastered the art of soldiering long before many of those commanded by him were a twinkle in their parents’ eyes. Thomas Jefferson served as president upon Mansfield’s birth in 1803, and he began his martial career at West Point in 1817. After graduating second in the class of 1822, the new second lieutenant joined the ranks of the elite Army Corps of Engineers. His duties took him south to build defenses along the Atlantic and Gulf coasts.
He proved his gallantry and valor during the Mexican War. Mansfield joined the staff of Brig. Gen. Zachary Taylor as chief engineer, fighting at the head of small commands at Fort Brown, Monterey, where he suffered a wound, and Buena Vista. He received brevets of major, lieutenant colonel, and colonel in the Regular Army.
After the war, Secretary of War Jefferson Davis appointed Mansfield to the Inspector General’s Department with the rank of colonel. He saw extensive service evaluating forts along the western frontier. When the Civil War erupted, President Abraham Lincoln appointed Mansfield to brigadier general in the Regular Army with duties in the Defenses of Washington. But he desired more active duty and lobbied for field command. His efforts paid off when the War Department assigned him to lead the Army of the Potomac’s 12th Corps. He took command two days before the Battle of Antietam.
During the early fighting at Antietam Creek, Mansfield’s Corps received orders to support Maj. Gen. Joseph Hooker’s 1st Corps, which had become stalled in the East Woods. While deploying the 128th Pennsylvania Infantry, Mansfield thought he saw some of Hooker’s men in the East Woods. He “at once came galloping down the hill and passed through the scattered men of the right companies, shouting cease firing, you are firing into our own men!” Men of the 10th Maine Infantry who had been fighting in the area informed Mansfield that the troops in the East Woods were rebels who had already wounded the Downeasters’ colonel. “Yes, yes, you are right…” he said to the Maine men. Then his horse was hit in the leg and a bullet hit Mansfield in the right chest, and passed out of his back, near the edge of the shoulder blade.
First Lt. and Adjutant John Mead Gould of the 10th Maine noted that Mansfield “Passing still in front of our line and nearer to the enemy, … attempted to ride over the rail fence which separated a lane from the ploughed land where most of our regiment were posted. The horse would not jump it, and the General dismounting led him over. He passed to the rear of the Regimental line, when a gust of wind blew aside his coat, and I discovered that his whole front was covered with blood.” Mansfield continued on and came upon the right company of the 125th Pennsylvania. Five men of the regiment formed a chair out of muskets and carried him to the rear of their line, where they left him to await the arrival of a surgeon.
Mansfield died the next morning at a field hospital at the George Line farm in Sharpsburg. His remains were sent to Baltimore, where they were embalmed before sent to Middletown, Conn., for burial. He was 58 years old. Six months later, Mansfield received a posthumous promotion to major general of volunteers.
Scott Valentine is a MI Contributing Editor.
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