United Fronts is a single-player mod that combines the campaigns of the original Call of Duty and United Offensive expansion with community created maps to form one large continuous campaign. It adds several new weapons and replaces almost all of the original weapon models. The mod requires the United Offensive expansion in order to play.
Another level that is part of the Polish campaign - Warsaw Streets. It takes place during the street fighting in the Polish capital in late September 1939.
Hope we also see the 1944 Warsaw uprising, could probably reuse the map