Line Infantry, how do you fight with them and why?

[FactionHeir]

The AI is pretty stupid with line. It just lines them up nicely and then you can start to envelop it and rout it within a minute.

Before you get fire by rank, just use 2 ranks. Afterwards go for 3-4 depending on space available. Once engaged, envelop from both side (don't charge). The AI routs fairly quickly.

[antisocialmunky]

It would be better if they just removed it and the player can form his own square.

[Hosakawa Tito]

Definitely don't use Austrian LI in melee before you research bayonets. I attacked a Polish Pike unit with 2 Austrian LI in melee and the Pikes were slaughtering them. I had to charge my General into the rear of the Pike formation several times to break them and save my infantry. I lost over 120 men & risked losing my General.

[Servius]

I also primarily use LI. I keep 12-16 units per stack. I always keep them 3 ranks deep for reasons others have said (staying power, fire-by-rank, can turn faster, can form box faster, etc.).

I tend to neglect the bayonet research line until I'm about to face Native Americans, as they have many melee units. When that time comes, I usually try to fly past plug bayonets and get to the real deal 3-4 techs down the path.

Also, when taking the field, I break my LIs up into groups of 2 or 3 units. I rarely bother to issue individual orders to each unit. I move them in a line until they're a bit beyond firing range, then I start using the 2-unit groups on the wings to envelop the enemy flanks and send my dragoons around behind the enemy line. Usually I'm able to completly surround the enemy formation in a hexagon- or octagon-like formation.

[Fisherking]

The French, Russians, & late Turks have the best melee. The Prussians and next the British have the best rates of fire other than Elite Units.

The Austrian Line is the all round worst. Lowest accuracy, reload, melee, and morale. Extra numbers do no offset their inferiority.

It would seem to me that the low morale is not justified in the game. Their infantry was known to be much more resolute than the officers who commanded them.

It was more the Spanish Infantry that was brittle in combat.