Alexander Magruder was born around 1826 in Kentucky. He married Margaret A. Wilson on October 12, 1858. They lived in Louisville, Kentucky, and Magruder worked as a merchant. By 1860, he owned $1,000 of real estate and $10,000 of personal property.
He remained loyal to the Union during the Civil War, and he mustered in as an adjutant in the 27th Kentucky Infantry on March 21, 1862. The regiment took part in the Battle of Shiloh, the siege of Corinth, the Battle of Perryville, the Knoxville campaign, and the Atlanta campaign. He was promoted to major on February 6, 1863, and he mustered out on March 21, 1865.
Magruder moved to Jacksonville, Florida, after the war. By 1870, he owned $13,000 of real estate and $45,000 of personal property. He died in Florida on October 30, 1870.