Hamilton Leroy Shields was born to William Cannon Shields and Elizabeth Finch on November 1, 1823, in Norfolk, Virginia. At age 18, Shields was among the cadets that relieved the state guard at the Lexington Arsenal. Shields entered the United States Military Academy in 1841, and learned amongst the future generals "Stonewall" Jackson, George E. Pickett, and George B. McClellan.

Following his graduation in 1846, Shields served in the Mexican-American War. After serving as second lieutenant to the Second Artillery, Shields transferred to the Third Artillery in March, 1847. On August 20, 1847, Shields was brevetted first lieutenant for "meritorious conduct" in the battles of Contreras and Cherubusco and was later brevetted captain for his conduct in the battle of Molino Del Rey.

In 1851, Shields married Caroline Hart, of Troy, New York. After serving as the judge-advocate of the Eastern Division of the Army until 1853, Shields resigned from the army on March 17, 1854, and became a lawyer in New York City. In 1857, through his wife's connections, Shields obtained land and became a farmer in Bennington, Vermont. Hamilton Leroy Shields died on November 24, 1889.

Much biographical information was gleaned from The Military History of the Virginia Military Institute from 1839 to 1865 by Jennings Cropper, published in 1915.