At the age of eight years, Alexander removed with his family to Woodstock, Connecticut, where he was educated at the Woodstock Academy and later at the academy in Wilbraham, Massachusetts. He left school to enter business with his father in the manufacture of cotton twine. At the outbreak of the Civil War he was the first man to enlist, as a private, but was later appointed by Governor Buckingham, Major of the Third Regiment, Connecticut Volunteers, and participated with his command in the first battle of Bull Run. He was afterwards made Lieutenant-Colonel of the Thirteenth Connecticut Volunteers, joined the Department of the Gulf and shared in most of the important engagements. After a short retirement, from ill health, he was ordered to raise and organize the Fifth Louisiana Regiment for the defense of New Orleans, which he commanded until ill health again compelled him to retire. He was subsequently appointed special agent of the Treasure Department in New Orleans.

In the autumn of 1865, Colonel Warner purchased a large plantation in Madison County, Mississippi, and was active in trying to secure just treatment for the freedmen, a course which he pursued regardless of threats and persecutions from the native whites. He was appointed Secretary of State by the military commander, Major-General of the State Melitia, was trustee and treasurer of the State University, six years a member of the State Senate, for part of the time its President and ex-officio Lieutenant-Governor, and three times a delage to the National Republic convention.

In 1877 Colonel Warner purchased a fine stock farm in Pomfret, Connecticut, later removing to “Sunnyside,” in the same town. In 1886 he was State Treasurer. He was prominently identified with various agriculture societies, while holding extensive interests in the west. About 1890 he resided in Baxter Springs, Kansas, was President of the Baxter Bank, and state Representative for two terms. He was a Mason and a member of the Loyal Legion Commandery of Massachusetts. After his wife’s death he made his home with his son at Point Pleasant, New Jersey.^{1, 2}