According to the Sigel-Belftimmugsbuch, Mittman traded between 1931 to 1959 with some of the forms being transferred to Tobinnus.
It also shows the marks on the base as being FM for Fritz Mittmann, with as engravers Sixtus Maier (SM) Andreas Ferner (AF joined) and Dr G Sollner (SO with umlaut) no mention of a single M.
The shape and design of the M might be able to establish the owner as many figures bear the M but each manufacture/Designer/Engraver seem to have a different style or shape for their M,which might help. The 20mm figures I believe were intended to be used as background figures in Dioramas, to try to give the illusion of depth.
They look like Franco Prussian war period.
Kindest regards
Bob