A couple of years ago a whole thread of 'war scenarios' was posted here I kept some and repost them here for your perusla and use
1The PCs live in a village which is attacked by deserters from the war
2 or The PCs village is attacked by enemy forces
3 The PCs surprisingly fend them off, but now have to hunt the survivors (if any).
4 However a messenger runs back to the village warning that the enemy is now regrouping and healing before heading back their way! They must move everyone out, and find a new place, fast!
5.Find the other survivors before the enemy does,
The enemy is scouring the area with war dogs/monsters (IMC I use Velociraptors!!) killing any survivors they find - the PCs may need to fight to save a captured tribesman
6. establish a safe camp (perhaps an old abandoned village site/ancestral cave/ruin)
7. They reach the safe camp only to find it infested with monster X (Vermin, Goblins, OwlBears) which the PCs need to clean out - or find another site
8. defend themselves as they try and survive the enemy occupation and/or
The villagers need to build a camp, fortify the area, collect weapons, hunt and gather food, keep everyone happy (this is the Roleplaying session) - throw in whatever random encounter you like
eg 8a the few remaining pigs the tribe has are going missing - it is discovered that they are being stolen by monster Y that lives under the new camp or
8b The camp's food source goes (Maybe an accidental fire), PCs must find a new source of food (Perhaps even hunting down monsters to eat).
9. recapture their home village
The tribesman are trained and the PCs ready to make an attack against the invaders and drive them out.
Other Missions
Steal the Enemy god (Major Artifact giving +5 Morale Bonus to their attacks) - PCs need to sneak into the enemy camp and steal/destroy the artifact
Release the Prisoners - Enemy has capture a VIP, the PCs go in and rescue him (imc the VIP was an old man and now crippled. He asked the PCs to kill him instead - very tragic)
Defend the Pass - PCs and a band of 100 warriors sent to fortify and defend the Mountain Pass
Call out the Champions
Peace Negotiations - (Non-combat) PCs are members of the delegation meeting with the enemy forces to make call a truce
The shaman or a PC (His apprentice?) recieves some visions; first, that their forces are dieing/going to die. The second reveals the whereabouts of some item/weapon/whatever which must be retrieved, then gotten into the hands of the most able warrior of the tribe (This weapon one of the PCs could eventually inherit, when they become powerful enough to be considered the highest level member of the party). It's guarded by traps, and perhaps some puzzles.
The refugees, still depending on the PCs, are approached by new inhabitants of the area, an enemy to their enemy, or to some whom they have had skirmishes in the past. The PCs then become the spokesmen, trying to negotiate trading terms, or perhaps have these new 'allies' help their tribe defeat the enemy
One of the females gives birth to a child that is half fiend, tiefling (Whatever race they happen to be), half-dragon, or somesuch. The Shaman could leave what to do about the child up to the PCs, as a test of their character, or they may need to negotiate what to do about it.
The Pcs now have to figure out Why the female gave birth to a 'tainted' baby. Is there such a creature in the hills? Some dirty secret of the tribe?
The PCs, as further bastions of the war effort, look to make deals with a monster near by, convincing it to help them (Mr. Ettin, if you go to the front lines, we'll give you a goat every month).
Monsters. Just monsters. Maybe some stirges are building a nest nearby (it's breeding season), or something similar with giant ants.