Pretty vague description (and most likely inaccurate), but if you've read the book, you'll know which one I'm talking about. Thanks!

That's an easy one! I couldn't remember the name of the book but a quick search using BookBrowse's handy "BookFinder" (cross referencing "in time of war" and "Russia" reminded me of "City of Thieves": http://www.bookbrowse.com/reviews/index.cfm/book_number/2161/city-of-thieves - which I think is the book you're after :)?

The BookFinder is one of the tabs at http://www.bookbrowse.com/category where members (and to some extend all visitors) can search for books by time period, geographical setting a wide variety of themes.