Jefferson Davis was a well-known figure long before he became President of the Confederate States of America. He was a graduate of the United States Military Academy at West Point and served as a member of Congress from Mississippi, first in the House and later in the Senate. He was a war hero in the Mexican War and was wounded in the Battle of Buena Vista.
I have read very little on the subject of the Mexican War, but one of the books sounds intriguing: The Battle of Buena Vista; With the Army of Occupation for One Month by James Henry Carleton.
Davis was appointed Secretary of War by President Franklin Pierce and is considered by some historians as the best to hold that office. After serving he returned to the Senate but resigned his seat after Miss. seceded from the Union. He was in his rose garden when he received the telegram that he had been elected Provisional President of the Confederate States of America Provisional Government.
Another biography on the life of this famous man that you may wish to read is: "Jefferson Davis, American" by William J. Cooper.