So in reality the events occur in a stream starting from the beginning of the Viking campaign with the warning about the Vikings and ending at 1453 with the "it's over message". So if I was to change the start date of my early campaign to 1065 and click end turn, would I be informed that William the bastard of Normandy has a arrived, but the game wouldn't end as that's determined by the end date right?

Anyway with the mod I'm working on there isn't much I can do as either way I lose. If I do set the start date to 087 and add on the one at the beginning it will remove any troublesome events, but will also get rid of the arrival of the Mongols, Swiss and Burgundians. So it looks like I'll just have to work around it.

Many thanks