It is time to reveal more on the next volume, now that the intended date of mid-May is approaching for publication. The first volume had a blue cover and therefore the second will have a white one. You already guessed right... indeed, the third and fourth will follow with a red and orange cover.
This will have a wonderful effect on your bookshelves, once the entire series is complete!
Furthermore on the cover of the first three volumes the Prince of Orange will be displayed during some epic scenes of the 1815 battles.