Heroes of Battle: Dungeons & Dragons 3.5 Mass Combat
Wizards of the Coast
There's some interesting approaches to designing a batllefield adventure which is actually pretty cool.
There is also some art from Doug Kovacs, also cool.
There's also feats and prestige class that are not as cool.
Great conflicts erupt between rival nations and threaten to sweep across entire continents. As armies clash in epic battles, the actions of a handful of bold heroes can turn the tide of war. Whether in the thick of combat or on a secret mission of dire importance, brave champions have an impact that echoes across the battlefield and resounds through the ages.
This supplement for the D&D game reveals the pivotal roles characters can play in the midst of great battles. With rules and options for creating or playing adventures on and around battlefields, Heroes of Battle plunges characters into wartime situations and challenges them with climactic battles of epic proportions.
Heroes of Battle provides everything one needs to know to play a battle-oriented D&D campaign. You can build military characters with new feats, spells, uses for traditional spells, and prestige classes. Information is given on tools specific to the battlefield, including siege engines, weapons, magic items, steeds, and other exotic mounts. Battlefield terrain aspects are discussed with plenty of illustrative maps and new rules. Specific types of battlefield encounters are discussed in detail, and the book provides specific detail on designing battlefields.