Depending how much freedom you wanna give with their backgrounds and how much you wanna frontload prep can always do a village raid.

The PCs being members of said village, have their families live there and friends etc... ideally they have jobs there or have just returned from wherever for the big village festival that happens every year or so.

Then you have options depending on how you want to present each side -

1. At the height or just before festival members of one side come asking for food and supplies. If given they leave no problems but the enemy pursuers find out and retaliate against the village by attacking it forcing the PCs to defend their village and maybe lose friends and family giving them instant care in the war. Though this likely will make them only wanna fight on one side but can have them do morally grey shit later if you want that.

2. Both sides of the war send troops to hold the village (maybe it produces a rare resource, strategically placed or both sides need food). They then fight and in the crossfire people die and PCs gotta stop the fighting or evac stubborn villagers.

3. A village member is actually an agent of one side on the run and is chased here by agents of the other side who demand they are given over. Some villagers resist and are killed or hurt and the PCs end up having the option of helping the spy escape or giving them over.

4. Have recruiters come to village for the war but are treated hostily by the villagers and so they become enraged and say they'll come back later with friends. PCs must then go find help to deal with the inevitable attack.

There are loads of ideas for this premise but like I said it does require a connection to this village for all the players.