The decision starts with rules, and the kinds of games I want to play in this campaign setting. The look and feel I am after, primarily, is a table full of large, ranked and uniformed infantry battalions, cavalry regiments and artillery batteries. Massed battles. Yes, I'm interested in skirmish (1 figure = 1 combatant) wargaming as well. But it's a secondary goal within this campaign. At least for now.
Three sets of rules are contending for my gaming attention at the moment. The first is Hearts of Tin, from Ross MacFarlane (for much more, please see his excellent blog, in my list of links). These rules call for infantry and cavalry units consisting of three to five bases, of consistent but not restricted size. The second is The Portable Wargame, by Bob Cordery. His rules allow units to be organized in any way at all, so long as a unit fits within a hex on the Morschausen-inspired game table. Finally, I'd like to give Volley and Bayonet a try. For these rules, units are formed on large, square bases.
In order to be able to play any of these rules with my collection, I plan to assemble my units as follows.
Infantry battalions will be formed in units of thirty figures, based on five stands of six figures each. The figures will be based in two lines of three, on 30mm square bases. For Hearts of Tin, the units will be fielded as they are. For The Portable Wargame, units will consist of two of these bases (so, twelve figures). Two Portable Wargame units can be fielded from each Hearts of Tin unit, with an eye toward taking advantage of some alternative rules Ross MacFarlane experimented with for keeping units from the same parent formation together. For Volley and Bayonet, four of the five stands will be placed in a deep column, two by two.
Cavalry regiments will be formed in units of ten figures, again based on five 30mm square bases, with two figures per base. Units for The Portable Wargame and Volley and Bayonet will be fielded as for the infantry.
Artillery batteries will be formed in units of two guns, each on a 30mm square base (assuming they fit...I need to experiment with this). Each battery of two stands will form a single unit for both Hearts of Tin and The Portable Wargame, and will be placed on a 60mm square sabot base for Volley and Bayonet.
That's the plan, as it stands now. However, I am considering reducing the number of infantry stands and cavalry stands per unit from five to four. I hesitate, because I don't have enough experience with Hearts of Tin to know whether I will regret being able to field five-strong units. And because I want my units to be quite large and formidable on the table. Thirty figures just look better than twenty-four.
However, using twenty-four infantry per battalion has two advantages. I have several units for which I have only twenty-four figures anyway. And, for those for which I have thirty, this will free up figures for use in skirmish wargaming, based singly. Finally, I may wish to reflect casualties by placing individual figures behind my massed ranks and removing them (one per "base" lost in Hearts of Tin, or per strength point if using an alternate rule for unit quality in The Portable Wargame) instead of whole stands. This would preserve the look of the unit until it routs away in disgrace, rather than seeing it dwindle strangely in size and frontage.
More experimentation is required to come to final approach.