МИТАВСКИЙ ДРАГ. ПОЛК

See under:

http://www.museum.ru/museum/1812/Library/podmazo/shefcom_m.html

Since, Mitau is a place, some people drop the "ski" when using English for the name (thus Suffolk Dragoon Regiment rather than Suffolkski Dragoon Regiment). Others like to keep the "ski" in the name of a unit.

The English version is used for units with other place names (so Lithuania Dragoon Regiment rather than Littow being the Baltic origin of Литовскиій).

The important point is to be consistent (or use the spelling of a good "same language" reference source; for example, that of Alexander Mikaberidze).

Your call, so good luck. - R