Charles Smith Hamilton (November 16, 1822 – April 17, 1891) was a career United States Army officer who served with distinction during the Mexican–American War.

He entered the United States Military Academy in 1839 and graduated in 1843, standing 26th out of 39 cadets; he was a classmate of Ulysses S. Grant, Christopher C. Augur, Joseph J. Reynolds, and several other men who would go on to become generals in the Army.

He was officially promoted to second lieutenant on November 17, 1845, and was assigned to the 5th U.S. Infantry, serving in the Army of General Zachary Taylor in the early phases of the Mexican–American War.

[2] Hamilton was eager to return to active service and accepted commission as colonel of the 3rd Wisconsin Infantry Regiment on May 11, 1861, just a month after the attack on Fort Sumter.

[2] Immediately after arriving in the field, Hamilton was promoted to brigadier general and placed in command of a brigade in Banks' division of the Army of the Potomac.

[2] In the Fall and Winter of 1861, Hamilton's brigade was engaged in securing the Union defensive line along the Potomac River in western Maryland and Northern Virginia.

"[5] Before the month-long siege preparations were complete, Hamilton was transferred to the Western Theater where he commanded the 3rd Division in the Army of the Mississippi at the battles of Iuka and Corinth.

When Grant ordered him to Vicksburg to serve under General John Alexander McClernand, Hamilton offered his resignation from the U.S. Army on April 13, 1863.