A number of years ago - pre internet and Ebay - along with painting miniatures I also collected postage stamps of the WWII era, particularly the AXIS powers and Occupied territories. Interesting history in them but also an area where I could also afford and collect an almost complete set of stamps. (Much more fun pre-EBAY.)
One aspect of stamp collecting I found interesting was the specialist. A dealer told me of collectors that not only collected things like ducks on stamps or flags but, also specifics such as windmills, chickens and barbed wire!
I find one of the charms of flats is the extensive subject matter outside of the military sphere - where else can one find a medieval fire fighting brigade though not so many chickens I think?
Personally I have found my collection to wander a bit from Napoleonics, 30 Years War and Alice in Wonderland but, I seem to have a concentration in medievals, ancient Egypt and the French army of Louis XIV and XV.
I have read of flat collectors who concentrate on specific engravers such as Morhr. (Great choice there by the way!)
What about you? What do you collect? Are there any specialist collectors out there?
Mark