Correspondence, journal, speeches, writings, military orders, scrapbook, and other papers relating to Civil War campaigns, the post-war Army, railway building in the Mississippi Valley, life in China in the 1880s and in 1900, the Spanish-American War, Republican Party politics, and the interests of Wilson as a biographer. Includes the typescript of Wilson's book titled The Life of John A. Rawlins (1916) and extracts of Rawlins's letters.

Correspondents include Charles Francis Adams, Adam Badeau, Simeon E. Baldwin, Tasker Howard Bliss, Andrew Carnegie, Henry Clark Corbin, E.H. Crowder, Shelby M. Cullom, Charles A. Dana, Grenville Mellen Dodge, Stuyvesant Fish, Hamlin Garland, Frederick John Kingsbury, Robert Todd Lincoln, Henry Cabot Lodge, William McKinley, John Bassett Moore, George Haven Putnam, Whitelaw Reid, Theodore Roosevelt, Elihu Root, Francis Lynde Stetson, Moorfield Storey, Oswald Garrison Villard, Paul M. Warburg, Horace White, Edward Francis Winslow, and John Russell Young.