The Clemens Brentano Collection at Mainz University Library includes numerous autographs. These include correspondence and several manuscripts by Clemens Brentano and his immediate and extended family members, as well as individual items from this circle. The largest part of the collection consists of autographs from the Nachlasse (written legacies) of Bettina von Arnim.
The collection dates back to Franz Dessauer, who wanted to found a Brentano museum. For this purpose, together with the publisher Pattloch, around 1928, he collected, among other items, Brentano family manuscripts. Due to the turmoil of war, the plan for a museum fell through. The Brentano House in Aschaffenburg was destroyed. The collection, however, survived the Second World War unharmed in the armored safes of the Pattloch bookstore.
Peter Baader: Die Brentano-Sammlung und die übrigen handschriftlichen Bestände der Universitätsbibliothek Mainz. In: Jahrbuch der Vereinigung "Freunde der Universität Mainz" 9 (1960), S. 9-36.