can I cancel an adventure?

I just started my first adventure to see what happened but after having a look my army isn't ready for it.
if i cancel the adventure do I lose it, even if I haven't attacked anyone yet?

once started, that's it.

Is it a two player adventure? Can you invite someone else on to finish it for you so you at least get some loot?

You could do some of it, and at least get some credit

What adventure was it? If its traitors, its worth doing a couple of the camps for really good xp. Check the guides to help you minimize losses

yes, you can but you'll lose the adventure and the loot