"Titular" means: only by name.

Maybe he means here (Hanoverian artillery, I presume ?) what in the Prussian army would be the rank of "Stabs-Capitaine". These were in charge of a company belonging to one of the staff officers of the regiment. They administered and led the company, but all the financial benefts were reserved for the staff offcier: the "Chef" of the company.

The next rank a "Stabs-Capitaine" could get was the "wirklicher Capitaine" who owned a company by himself, being its "Chef".

The company system was abolished in the Prussian army in 1808, but the rank of "Stabs-Capitaine" was abolished as late as 1815.

However, the title "Titular" makes the impression as if Scharnhorst only had the formal rank, without any captain's tasks ?

Does Tilman Stieve perhaps comment on this Titular-captaincy ? When did Scharnhorst get this promotion ?