They're thought as infantry-based nation, while most of the other nations seems to be more tank-, ship- or plane based. As a second point, they're an addition for the lonely eastern block.
Historical they're based on the communist local fighters against the Nazi invasion, partly described in http://en.m.wikipedia.org/wiki/Partisan_(military)
We should also add the Molotov (became fame when the Fins destroyed ~80 sowjet tanks without losing much manpower) as the default AT weapon. The partisans are also very good saboteurs. The biggest problem'll be the lack of good planes (even when supported by the sowjet union)
Please say, when I should add sth
