Contains primarily incoming correspondence received while Babcock served as private secretary to President Grant, with a large portion of the letters concerning Grant’s attempted annexation of Santo Domingo and Babcock’s Whiskey Ring trial. Many of the letters have a penciled draft of Babcock’s reply on verso. Also contains family correspondence, notably a series of courtship letters from Orville Babcock to Annie Campbell prior to their marriage. Some family correspondence extends beyond Babcock’s death in 1884, including several letters from Campbell Babcock to Annie Campbell Babcock during his service in the Spanish American War.