This file contains more than 12,000 incoming letters, which parallel the outgoing correspondence in Series I. Again, the letters are arranged chronologically. There is a good deal of official and semi-official correspondence describing du Pont's cruises and promotions as well as naval policies and practices. Of particular interest are the letters received from British diplomats and naval officers during the 1840s and 1850s describing operations of the Royal Navy. There is a significant series of correspondence for the period of the cruise of the Minnesota. Letters received from William B. Reed, American minister to China, document the negotiations that led to the Treaty of Tientsin. Letters from Samuel Wells Williams and Edward W. Syle describe the American missionary movement in China and efforts to eradicate the opium trade.

The incoming letters also contain important correspondence from the Naval Efficiency Board years. The letters that were written to challenge the board's decisions reveal a good deal about the politics of the pre-Civil War Navy. In addition, the correspondence from the Civil War period contains many letters that du Pont's subordinate officers sent to him after the attach on Charleston. The largest single block is from Gideon Welles. These trace the secretary's growing disenchantment with du Pont's strategy and leadership.

Series II. also documents du Pont's superintendency of the 1853 Crystal Palace Exhibition and his role as official escort for the Japanese envoys in 1860. The numerous letters received by him during the visit of the Japanese show that many American were fascinated with the East Asia and thought that Japan was becoming increasingly important in the international political arena.

This series included copies of original items found in the Winterthur Manuscripts. Many of the transcripts were prepared for Sophie du Pont and Henry A. du Pont. Of particular interest are typescripts made from Naval War Records (now the National Archives) and copies of 180 letters from Henry Winter Davis.