Battle Formations

From the introduction:

Warfare is a staple in most fantasy stories. A huge lot of them like to depict vast armies stretching across the horizon, arrows flying across the sky, massive phalanxes clashing with shield walls and heroic cavalry charges. Although D&D is a game focused on small groups of characters, such epic conflicts are an awesome resource for adventures. Because the battlefield is a nasty and turbulent place, the characters can be thrust into new situations and new dangers at a moment’s notice.