Irvine Shubrick's letters to his brother-in-law, Samuel Francis DuPont, contain detailed references to naval matters, including the movement of ships, controversies, and their fellow officers.

The Crofton and Shubrick families were descendants of a prominent French American diplomat and businessman, Victor Marie du Pont (1767-1827), and represent middle-class American families in the mid-to-late nineteenth century. The collection includes a small amount of material from the Shubrick and Crofton family from the nineteenth century to mid-twentieth century.