Chosen more or less at random, the pose being more a deciding factor than any particular personality from the set.
Whose who, According to the boxart and PSR
Abner Doubleday
In Charge of the cavalry. I painted his Outfit a bit more fancy to reflect his future Career.
George Armstrong Custer.
Joshua Lawrence Chamberlain
Louis Philippe Albert of Orleans. (Philippe d'Orléans, the Count of Paris) As noted at PSR, an odd sort of Personality to add to the set.