18e de ligne was about 2200 strong according to colonel Pelleport, and I would agree with Digby Smith that as a rule of thumb the French regiments were about half strength compared to the start of the campaign.

However I ask myself - why starting a battle in such a formation, a whole corps - one battalion behind each other - it is also interesting to read on how this formation than continued and how Ney used it.

It seems, that those clumsy big columns of Drouet, so much unter critic at Belle Alliance were much in use by Ney at this day of battle.

The memoires of Pelleport are an interesting read, easily to download from our friends of google.