Many years ago I read an online note of some kind (or perhaps it was in a magazine) from Brent Oman of Piquet fame. He was explaining the Rule of Twelve. This week he mentioned it again on his blog: Wargames and Stuff. It bears repeating in part here:
THE RULE OF TWELVE: Simply put, any battle can be reduced to a 12 unit or so limit of the core type of unit in the army. Obviously, in all but the most horse centered culture, this will be 12 units of infantry. Artillery and cavalry would then be proportioned off of the 12 infantry units.
I'm not sure he's talking about reducing (or bath-tubbing) any historical battle to only twelve core units and that's not how I originally imagined it anyway. I had always thought that collecting miniatures for a particular historical project could be made much easier by adhering to this rule. For instance, one could approach even a monster genre like Napoleonics with this rule. And I always thought of it more strictly than Brent. He's advocating 12 core units (i.e. infantry) and adding other unit types in proportion (i.e. artillery and cavalry). So a typical French Napoleonic army with this method would see 12 infantry units (two or three brigades, depending on the organization...so, say one division for the example's sake), perhaps one or two artillery units and brigade of cavalry made up of two to three units. Thus, a maximum of say 15-17 units. My thought would be to have a 12 unit maximum (or a baker's dozen thirteen, if so inlcined). For example, eight infantry units (a small division), one artillery battery, two cavalry units (one brigade) and one or two electives (oh, maybe another brigade of cavalry or a couple of light infantry units). In the Napoleonics example, one could comfortably collect a number of different armies with this method. Each would have the basic horse and musket Napoleonic structure of an infantry division and accompanying cavalry brigade with some room for tailoring to national organization characteristics.
Of course, this assumes that one could stop at the twelve (or thirteen units). Anyone who has known my past Napoleonic collections (yes, plural) would know the folly of such a suggestion :)
This has sorta worked with my Carlist collection wherein my Carlist army has nine infantry units (four of which are skirmishers), two cavalry units, and one artillery for a total of 12 units. The Isabellinos have nine infantry (three of which are skirmishers), two cavalry units, and two artillery, totalling 13 units. So far so good! But where do I fit in the Foreign Legion that fought on the Isabellino side (four infantry, one cavalry, one artillery)? Hmmm, maybe as a third army?
Let's see, how did that work with my ImagiNation project? The army of Le Drand-Duc de Gourmandie has six infantry units (two of which are irregulars), three cavalry units, and two artillery for a total of 13 units. But damn...that doesn't include the two heavy artillery I'm adding and the other two cavalry units. Time to re-think this rule....