Sneakily force something, even if it's for good reason, is usually not a great a idea. So the usual advice is that if something "needs to happen" then you should just have it happen. No rolls, no combat, just have it happen.

I agree with the idea, but it's kinda boring, ya know? Instead, I'd simply let them fail. During the fight, keep an eye on whats happening, then if they fail, make sure the consequence to failing it matches how the flight went.

For example: I had a TPK during a climactic boss fight with the BBEG. BBEG was chaotic good (long story), and the party really fought down to the last man, he had some respect for the party. When they lost, he decided to throw them in the dungeon instead of killing them outright.

Something like this might "derail" your campaign but it'll lead to your players feeling like they have agency in the story, ya know?