I'm planning a new 6mm Republican Roman army and would like some advice on the best way to represent them.  Current plan is to use 24 Baccus figures per Maniple (which I understand would normally comprise six ranks of 20).  The options really are two lines of 12 or three lines of 8.   I'm tending toward the latter but would be interested if anyone has any thoughts / experience with building this army.  Thanks.    Phil.

I've no experience with them but l have seen some based as 3 or 4 ranks of 12. I liked the look of 3 ranks of 12 as it still leaves you some space to create the mini diorama effect that greatly enhances the look of the 60x30 base. 

I think the answer depends upon the level of abstraction (figures to real men and command level) you are using', how you have based up other troop types, and some of the assumptions and mechanics in the ruleset being used.

On the basis of your 1:5 scale, I would suggest the 3 ranks of 8 figures best matches the authenticity of the 6 ranks of 20 real thing. I assume though any Greek hoplites you have are based at least 4 ranks deep, Persian sparabara 5 ranks and Macedonian phalangites 8 figure ranks deep. If they aren't then a shallower smaller formation might be more appropriate.