This month, I reviewed John C. Calhoun: American Portrait by Margaret L. Coit. It won the Pulitzer Prize in 1951. It goes over his entire life and explains his philosophy as a states' rights man and a Unionist.
John C. Calhoun is considered by many to be the most important Vice President of the United States who never became President. Along with Henry Clay and Daniel Webster, he was part of The Great Triumvirate. From the War of 1812 until the Compromise of 1850, these 3 men were considered the most important Americans, overshadowing the Presidents of this time period.
https://www.goodreads.com/book/show/1542187.John_C_Calhoun?ac=1&from_search=true&qid=2bqevxRuZH&rank=2