mass rebellions

[FoundationII]

I know there are mass rebellions when you just conquered 100% of europe. However I was playing GA with the germans in easy (I wanted an easyand relaxing game) and only conquered about 65% of Europe. Suddenly three quarters of my provinces were rebelling, even Switserland who I was closly monitoring from the start and almost had all buildings available (including relinquary, inn,...) and all the neighbouring factions attacked me, even my allies. Five years later a lot of these provinces rebelled against the rebels because they were still loyal to me, now I have lot's of generals with their maximum command level but my happiness in all my provinces are way down (I still get at least 5 rebellions each year)
How could this happen?

[Metal Storm]

Don't forget you can't see a Spy. A high Valor spy can cause havok

[FoundationII]

That would explain 1 or 2 rebellions maximum 5 but I had more than 50 and that doesn't explain why all my allies chose to backstab me the same year.

[motorhead]

Once you gain 60% of the map province loyalty becomes more of a problem. It's just the way the game is designed. Put at least one spy in every territory, keep your empire connected thru ships and ports, keep your king in a centralized province with a port. Make sure your provinces are of your religion - send in priests/alims to convert. Build church/mosque, border forts and town watch in all your provinces. Always keep at least 100 troops in every garrison. Certain provinces are more prone to rebellions: portugal, ireland, scotland, latvia, lithuania and serbia-or-croatia. Extra spies and larger garrisons for them. As long as loyalty stays above 120% you'll NEVER have a rebellion or re-emergence in your lands EXCEPT for the papacy. Always leave the pope at least one province.

edit: if you had 50 rebellions it sounds like your ruler got disconnected from his empire. Once you get roughly 25 provinces your king should just stay at home. Hold down the shift key on the main map and your provinces will show colors for loyalty: red - rebellion very likely, yellow - possible rebellion, green - loyal.

[Togakure]

Also be sure not to have your King cut off from the rest of your provinces. The province he is in must be connected to the rest of your empire somehow, either directly by an adjacent province that you own, or by an unblocked trade route via your ships over the sea. If he becomes isolated in a province not connected to the rest of your empire, your entire empire will suffer a large loyalty drop, usually causing mass rebellions.

[FoundationII]

When I played the almohads I didn't have any problem with conquering more than 60%, I only started to have problems as soon as I started to conquer the 2 last factions (turks and egyptians) I needed to place garrisons in their provinces because they were very loyal. The rest only became a problem as soon I conquered the last province, but that was in 1.0 can it be something connected to the patch?

[FoundationII]

That could be the reason, my king had invaded Ireland and the port was destroyed, so he was trapped.
Thanks TogakureOjonin