The collection contains correspondence, reports, and documents of Beauharnais, primarily accumulated by him in his capacity as viceroy of the Napoleonic Kingdom of Italy (1805-1814), relating to European military affairs during the Napoleonic era. Also included are papers documenting Beauharnais' position at the Congress of Vienna (1814-1815), his establishment in the Bavarian duchy of Leuchtenberg (1817), and his later life as Prince d'Eichstätt (1817-1824). There are approximately 6000 letters and reports received by Beauharnais from all the important military and administrative officials of the French Empire, including Napoleon I, Louis-Alexandre Berthier, Henry Clarke, Jacques Menou, Auguste Sorbier, Joachim Murat, Joseph Fouché, Sextius Miollis, and Louis Baraguey d'Hilliers, and such notable Marshals of France as Louis-Nicholas Davout, Jacques Lauriston, and Auguste Marmont. The correspondence deals, for the most part, with military matters, but also covers naval and maritime affairs, finance, engineering, fortifications, and the civil administration of the Kingdom.

Also present are extensive files of financial reports on the budget of the Kingdom compiled by Michel Hennin, Treasurer of the Crown, including the estates at Chiaravalle, Galliera, Bologna, Pelucca, Ancona, and other Appanage districts; files of Beauharnais' secretaries and aide-de-camps, Antoine Darnay de Nevers, Antoine de Re, étienne Soulange-Bodin, Auguste Bataille de Tancarville, and Baron d'Eichthal; general reports on military and state affairs; military statistics; documents and notes on the campaigns of 1809, 1812-1813; correspondence and reports of Italian generals and administrators, such as Domenico Pino and Marie-Francois Caffarelli; inventories, stud-farm records, budgets, and expenses of the royal households at Malmaison, Villa Bonaparte, Pelucca, and Laferté-Beauharnais; cash accounts, and letterbooks of Beauharnais' outgoing correspondence. There is also a file of social correspondence of Augusta-Amalia, Beauharnais' wife, containing letters (1817-1849) by various European dignitaries, and records (1806-1823) of her personal finances.