According to the Rangliste for 1863 there was a v. Hiller who was commanding Infanterie-Regiment Nr. 44, which was garrisoned in Thorn.http://babel.hathitrust.org/cgi/m/mdp/pt?seq=554&view=im...
The regiment was part of the 3rd Brigade, 2nd Division. The Division consisted of the 3rd and 4th Brigades, and I would think that if he commanded a brigade during the war it would have been these. Later Rangliste or the regimental history should indicate whether this is the case.
A regimental history was published in 1885:
Link zu diesem Datensatz http://d-nb.info/573031444
Titel Geschichte des 7. Ostpreussischen Infanterie-Regiments Nr 44 von 1860-1885 / Erich. Die sämmtl. Anl. sind bearb. v. Toeppen, Secondlt.
Personen Erich, Fritz ; Toeppen, ...
Verleger Berlin : Mittler
Umfang/Format VII, 339, 220 S. : Mit 1 Titelb., 4 Skizzen im Text u. 3 Pl. ; 8
This book might be in the possession of the Library of Congress, New York Public library, University of Michigan library. Within the last two or so years some of these regimental histories have been digitized, and I would think that the next few years will see many more as many are now in the public domain.