William Marmaduke Kavanaugh was born near Eutaw, Alabama on March 3, 1866.

Kavanaugh then entered politics and was elected sheriff and tax collector of Pulaski County, Arkansas where he served from 1896 to 1900.

He then turned his attention to business and began a varied career in banking, street railway, and gas supply.

Kavanaugh was elected to the United States Senate to fill the vacancy caused by the death of Jeff Davis.

He was the president of the Southern Association, one of professional baseball's principal minor leagues, from 1903 until his death.