This campaign is all about building a predecessor AND it's successor.
Examples; British Sherman M4A4 is succeeded by the Sherman Firefly (fairly large transformation between the two vehicles). OR Panzer III which was succeeded by the Panzer IV (a complete upgrade).
An example of something that DOES NOT qualify; M1A1 Abrams and an M1A2 Abrams (only small changes over the years. Too few and far between to create a different vehicle).
The exception; many countries have replaced it's aging fleet of vehicles with something more modern that fills the same general roll (Australia has replaced its Leopard I with the Abrams). In these cases each vehicle should have appropriate markings.
These vehicles SHOULD NOT have a generational gap (Sherman M4 being 'succeeded' by the Abrams.
The Rules and Regs
1). Kits (two) can not be started (will accept models with only a few pieces added; no more than 10%).
2). A (one) photo of BOTH completed models must be uploaded to the campaign gallery.
3). No generational gaps (no large spaces between service).
4. No 'What-ifs'. It can't replace something if it was never built!
One ribbon is awarded if a photo with BOTH vehicles is uploaded to the campaign gallery.