From Mr. Peter Klein in Wiesbaden, I have received the following detailed description of Herman Theodor Frobenius::

Herman Frobenius and his mother lived in Erfurt in summer 1870, but I thought he was there, because he was in the staff of the engineers of the fortress Erfurt (he was indeed). His profession was military engineer. After the war between Germany and France he served as teacher at the Kadettenschule in Berlin and also of the Vereinigte Artillerie- und Ingenieurschule there. After that time he spends some years as engineer at the fortress Strassburg. His probably last military engagement was being chief-engineer of the fortress Boyen at East-Prussia.

He was somewhat famous, cause in autumn 1870 he was the first German soldier climbing the wall of Lunette 53 of the forteresse Strassburg (than French), which was under siege. After 1900 he wrote a very nice small book about this episode, with some familiary backround

After he resigned from the army, he made some extensive journeys with his son Leo, which lead him e.g. to Sudan. He wrote a book after that (Die Heiden-Neger des Aegyptischen Sudan, publisher Nitschke&Loechner, Berlin 1893) and an article (Sammlung gemeinverstaendlicher Vortraege, Hamburg 1898: ...Die Erdgebäude im Sudan). I'm not in doubt, that he influenced his son Leo in this direction, what the official history about Leo Frobenius did not yet noticed.

In 1898 he published a biography of Alfried Krupp (Alfried Krupp. Ein Lebensbild, publisher Carl Reissner, Dresden und Leipzig, 1898).

In 1901 his military encyclopedia was published (Militaer-Lexikon, Berlin 1901). 1906 a two-volume exercise about the history of the Prussian military engineers from 1849-1886 was completed, today a very important book, cause most of the contained information burned 1944, when Harris bombed the archive in Potsdam. 1907 an expensive glory-book about the history of the Hohenzollern-family (to which the Prussian kings and the last German emperors belong to) appeared, 1912 the first volume (second never published) about "Unsere Festungen" (today another invaluable book) and 1914 (before the war) "Des Deutschen Reiches Schicksalsstunde", a book republished several times throughout the war. His two last books were "Schwestern der Schicksalsstunde", 1915, and "Kriegsziele und Friedensziele", 1916.
He also wrote in annual books and magazines, but I have not yet a list of his articles.

He and especially his son Leo had a good relation to Wilhelm II. Herman Frobenius was known as a very critical writer on current military issues.