What counts as the attacker's and defender's force in a campaign?

Question

Accepted Answer

The attacker's force is the warbands on its own player board. The defender's force is the warbands at the targeted sites, plus its board warbands when its pawn is at the attacker's site or a targeted site. Losses depend on force, not on the dice rolled.

Oath: Chronicles of Empire & Exile

What counts as the attacker's and defender's force in a campaign?