|French infantry in a loose firing line|
One could, theoretically, just represent the skirmishers, but most Nineteenth Century wargamers seem to opt for the close order supports. This gives a very Napoleonic look and is not IMO entirely convincing for, say, the Franco-Prussian War.
In reality the supports tended to reinforce and merge into the skirmish lines creating a heavy firing line. In fact, this was regarded as a notorious problem for control. But in terms of depicting units on the tabletop, it justifies an irregular, loose line somewhere between skirmish and close order.
For my ACW armies I went for the shoulder-to-shoulder Napoleonic look because I considered that to be the most appropriate, but I think a looser look would be much better for the Franco-Prussian War. But it's not just a question of spacing the figures out but of arranging them with an organic irregularly. This will, I believe, look a lot better aesthetically, though, of course, a 1" base is a very limited stage.
With this in mind, I find the balance of scale preference moving away from the 6 mm Baccus strips and back towards 10 mm Pendraken figures. My ACW infantry are 12 up in two ranks on 40mm x 25mm bases. The equivalent number for a 1" base would be 8 figures. For the looser look I envisage, 4 or even 3 figures would seem to be optimum.