Took Vilnius from the Poles. While it wasn't a terrible fight, it was a bit more a clusterfuck than I'd have liked, largely due to the fact that you can't damage the gate-walls of city fortifications for some reason. Otherwise, I'd have been able to rain cannon fire into the center of the town. I had to send my troops into melee where they were completely surrounded and outnumbered...
and they kicked ass. Having a large number of grenadiers while the best they had was line infantry and not a whole lot of them helps. Having bayonets while they don't also helps.
But that's not the end of it. Before I could recover my depleted troops, they send an even bigger army to lay siege to the city I just took. Seeing as this prevents troop replenishing and reinforcements weren't going to happen any time soon(the Russians were also attacking), I had to sally out. Outnumbered with ~1000 against ~1500, I ended up fighting the enemy off in several sorts of combat I usually don't find myself in - melee, using canister shot, that sort of thing. Despite heavy losses, the Polish were forced to retreat.
Then the Russians attacked. By this time, I had time to gather some reinforcements and catch their army outside the city. Ended up giving the Russian bear a bloody nose or two, giving time to consolidate and replenish my troops.