Where is your layout based?
I think what is meant is where are you basing your layout on?
Being WW2 I wonder if you are basing it on the continent where there are a lot of proprietary HO models available
ROCO, Fleischmann Lilliput etc do a range of military stock
Some stuff on eBay:
https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=military+trains&_sacat=220&_sop=10&rt=nc&LH_PrefLoc=2
until