evening's page

It's the dead of winter. The PCs, who have not yet met, are down on their luck. They've spent their last coin months ago. They've called in their last favor weeks ago and have been living just outside the law when they receive an unusual invitation.
The PCs are hired on as mourners at a funeral for a long forgotten sage who lived in a decrepit estate in a merchant district of the city. A sumptuous meal is provided at the wake and the PCs can't resist a free meal such as this. A roaring fire, coupled with copious amounts of rich food and drink provide the perfect recipe for...sleep.
The PCs awaken to the sounds of birds chirping playfully overhead and now notice that they are in the middle of a deep forest with rudimentary equipment that they must share to survive. There is also a journal resting on an overstuffed pillow next to the PCs when they wake up.

Check out Green Ronin's - "The Black Company Campaign Setting" (based on the books by Glen Cook)

It has rules for individual, company-scale and army-scale combat.

Command feats that let a character order units to perform special maneuvers and improve the unit's fighting ability.

Terrain, morale, magic, training, etc.

Most of the rules you are looking for (might) be in this book.