I have only lost once as the English. I foolishly invaded Wales with my King and both his heirs. I had decided to charge up the hill with all my cavalry, which proceeded to be shot down by the Longbowmen. After the battle I saw that both my heirs had been slain, and a few years later my king died of natural causes, causing me to lose my campaign.

However, there have been several campaigns I have given up on relatively early where I had failed to establish a solid position and was next to an enemy much stronger than me. These occur mainly with the one province factions. But I have also had a failed XL German campaign. That was quite a challenge - surrounded by seven hostile factions.