The Malcom's Maxims

Directly from the web page of Malcolm Mccallum, read some of his Maxims for Napoleon's Battles, devoted to Infantry:

XXI
Always leave 2-3" minimum between infantry formations front-rear to allow for possible combat withdrawals. Similarly, an infantry column should always have enough room on each flank to allow it to deploy from column to line as required.

XXII
If a firefight is sustainable, take the time to form line. Only if it is not, or speed is the prime concern, should a combat be attempted in column. Infantry columns are not an arm of decision but rather maneuver. For decision, use infantry lines, cavalry, or arty. If , on the other hand, a win in column can be fairly guaranteed and there is no serious counter-attack threat, it would be the preferred formation for attack since the unit would be properly deployed to take advantage of any gained breakthroughs.

XXIII
The addition of multiple infantry units into a melee mostly just provides more opportunities to get a good result. With two units, there will be two rounds at least. Therefore do not commit multiple units to a bad or excellent situation but only where the issue is in doubt and a win is more decisive than a loss or two.

Napoleon himself would endorse these sentences!

By the way, the Malcom's page is full of good material, not only about Napoleon's Battles (go to the 15 mmm Section) but also about campaigning in the Napoleonic era.

See a sample of his After Action Report of a refight of the battle of Talavera (with a surprising ending!) whose bicentenary we celebrated the 27-28th july.