You can download the maps for RBWar 6 from HERE. These are the high quality RB3D maps created by Murph (thanks Murph, the RB community appreciates your excellent work!!!)
Unzip the RBWar 6 maps (named mpkbd0.bmp, mpkbd1.bmp, mpkbd2.bmp and mpkbd3.bmp) to the data/multi folder of your RB3D installation folder but first back-up/rename your existing mpkbd0.bmp, mpkbd1.bmp, mpkbd2.bmp and mpkbd3.bmp files in the multi folder so they aren't overwritten with these maps.
Note: you do not have to use these maps for RBWar 6; the targets will show up on your kneeboard maps, they just won't have any target numbers on the maps; these RBWar 6 maps will show the target numbers on the maps.

Alsace Map

Flanders Map

Marne Map

Verdun Map