Drennen, nicknamed "Mac", was the 6th of 9 children born to Walter and Matilda Cornwell Drennen. He grew up on his family's Blount County plantation, and was taught by his older brother William at a private school there. He went on to study at Vanderbilt University in Nashville, Tennessee before he and another brother, Melville opened a branch of the company's mercantile business in the booming city of Birmingham.
In 1886 Mac was elected to the Birmingham Board of Aldermen, representing Ward 3 In Mayor A. O. Lane's third administration. Mac Drennen took on the role of president of the company as his brother pursued other business ventures and served as Mayor of Birmingham.
The Drennens resided in the former William Rushton residence at 2900 Highland Avenue, and attended St Mary's-on-the-Highlands Episcopal Church where Drennen served on the vestry and as senior warden. He was also a trustee of Children's Hospital and the Birmingham YMCA.
Drennen died on his 21st wedding anniversary. He was buried at Elmwood Cemetery.
- Cruikshank, George H. (1920) History of Birmingham and Its Environs: A Narrative Account of Their Historical Progress, Their People, and Their Principal Interests 2 volumes. Chicago, Illinois: Lewis Publishing Company. - via Birmingham Public Library Digital Collections
- Darlyne Drennen at Findagrave.com