For people who play Wargames, either with 'toy soldiers', boardgames or computer simulations - one of the great appeals seems to be the drawing of minute differences between similar troops - this unit moves a little faster, this one is less likely to retreat and so on.
Were such distinctions ever actually apparent beyond general role and perhaps raw/veteran/guard status? Did commanders actually take anything like it into account? Did anyone ever say "The Piedmontese are excellent swimmers - send them to take the ford" or was it more "Move some troops to the left"?
Asking specifically about the era of Napoleon, but would be interested in any period.
Someone else could give a better answer. Here' s mine: yes. There are several examples.
To start with: Napoleon said something like this " 2 Mameluks can defeat 3 Frenchman on horse, but 100 Mameluks equal to 100 Frenchmen. 1000 Frenchmen can defeat 1500 Mameluks. Such is the power of tactics and organization. " After the Egyptian campaign, created a unit of Mameluks and they are impressive in Auerstilitz.
Cossacks are legendary in raiding and harassing Napoleon armies in the Russian campaign. They are probably the best example you think of.
Napoleon also remarked "Austrians had better horsemen than the French but they don't know how to use cavalry" In one example of such statement: Napoleon' s marshal Davout is within grasp of his first defeat, but able to repel the Austrian simply by putting light infantry units against Austrian cavalry in a forest. Forest aren' t good for horses charge but the Austrian generals don' t have good intelligence in any sense of the word. This happened in 1809 Campaign.
Early in the revolutionary wars, the French started the mass conscription which resulted in a mass untrained troops. So in order to make sure the army don' t break. A battle often ended with the professional unit, inherited from the previous regime, and a unit of skirmishers doing the fighting. If that unit is winning, the rest joined. If not, they prepare to retreat. By the time of the empire, the conscripts became veterans. In 1809, the war in Spain took so much of these veterans, that the Austrian Minister believed (wrongly) that the French army in the east front is ripe for defeat against the Austrian Reform (in-progress) army.
Often barely trained, quickly formed Austrian units, often headed by bad officers, can't used the hollow infantry square formation that required drills. Instead, their squares is tightly pack. It is a much better target for artillery fires but it get the job done against cavalry.
The British do not have mass conscription. Their redcoats are better discipline than most due to them being professional. Because they need to cross sea to go back home, they are less likely to desert.
In Wagram 1809, the centre of the French army is composed of Italians and Saxons units. While the French Old Imperial Guards are at the back ready to kill them. The Italians and Saxons are recently formed, barely trained and are fighting for foreign overlords. They broke constantly. This is the most bloody battle up to that time in era. In the end, the Imperial Old Guard that had done very little if any fighting was used to finish off the Austrian. They are also the first to receive medical attention.
Sources:
David Chandler "The Campaigns of Napoleon"
John Gill "1809: Thunder on the Danube"
Rory Muir: "Tactics and the Experience of Battle in the Age of Napoleon"