On the orders of General Grant, General Alexander's troops are confined to the camp. Staying without fighting and waiting without doing anything influences the morale of the troops. At the slightest pecadille, everything turns into a drama! Blutch spends his time trying to escape and Chesterfield to bring him back to the camp. Until the day when François d'Orléans, one of the sons of the King of France, carrying the titles of Prince de Joinville and Vice-Admiral. He is there as military adviser and camp helper of General Mac Clellan. His passion: painting watercolours. And this is the way to relax the atmosphere: everyone with a brush! But during this time, Blutch and Chesterfield, they are sent on a mission to monitor the possible presence of the confederates in the vicinity. And this is not all rest! With this story based (as often) on an authentic anecdote, the authors lead us into a great historical-humoristic adventure where, as always, the army takes it for its own sake. Once again, Raoul has succeeded in mixing up their history and his own.