150,000 records isn't all that huge. We have a receipts database of over 200,000 records with a table of related line items that several times that count.
150,000 images will be lot of images to manage. If you intend to link them into the database, you'll probably want store by reference container fields.
I think you'll find that separate files for each regiment will multiply your work and divide your your ability to do things with the database as a whole.
You should probably create a table that handles Regiments rather than having a different "database" for each regiment.