I was playing a campaign when I found I couldn't take an african country because it was already being besieged by the French, who I'd also just taken out of the game.

I tried retreating & re-invading.

I tried loaning troops to the country to help lift the siege.

The only thing that worked was when I left the french capital allowing them back into the game, which then allowed the african country to lift the siege. But this meant I had to recapture the French capital & fight more partisan troops.

Events that got me here where as follows:

1. I liberated Tripolli from French, but then withdrew.
2. French invadid Tripolli & put it under siege.
3. I re-invadid tripolli & beat the french there on the same turn my armies annixed France.