Where to make a start
The National Archives nationalarchives.gov.uk/help-with-your-research/research-guides/medieval-early-modern-soldiers
Guide to locating early soldiers (including some Scottish records).
Medieval soldiers www.medievalsoldier.org
Names of thousands of soldiers serving the crown (mainly, but not only, in France) in the period 1369–1453 and details of Military Pardons.
Parliamentarian officers british-history.ac.uk/no-series/cromwell-army-officers
The most comprehensive list of Civil War Parliamentarian Officers, sometimes with additional genealogical information.
Civil War Army Lists archive.org/details/armylistsofround00peacuoft
Details of early Royalist and Parliamentary officers from 1642.
Militia records findmypast.co.uk
Early militia records for Plymouth (1625–1831) and York (1509–1829). Most early Militia records are held locally – use TNA Catalogue ( discovery.nationalarchives.gov.uk/) to locate them (search for Militia and restrict the search to Other Archives).