I managed to play a complete game and lose to the Royalists by 6,490 to 642. I tried all I could to get my morale down to below 25 to trigger a sudden defeat but couldn't get it below 58.
I even put Cromwell and several other leaders on a boat and had them bobbing around in the North Sea for a couple of years. Hope they were sea sick.
I promise to play more seriously in future.