The computer cheats!

[King Henry V]

I am playing a game as the English on High with the BKB mod, and I have conquered Aragon, the Genoese and the Venitians, plus taking Toulouse and Burgundy when they went rebel. I was at war with Hungary when the Danes sent their troops across the North Sea and landed in Mercia and Scotland, as I did not have any ships in the North Sea. They then proceeded to send their enormous fleet to annihilate mine, which they duly succeeded. This I can understand. I sent mercenaries over from Ireland to retake the lost provinces and trained some more troops to guards my shores. The Danes had not been excommunicated for attacking my ships, yet when I built one and unsuccesfully attacked a Danish ship, I got a message from the Pope telling my that if I did not cease hostilities with the Danes, I'd be excommunicated! The cheek of it! Then I had a few ships in the Med, off Sicily and in the Ionian sea. Yet the Byzantines still managed to land an Army in Toulouse. This frustrates me enormously! It's one rule for it and another for me!

[antisocialmunky]

I would suspect someone with that many posts to be a MTW oldie. Anyways though. If you have twice as many provinces than they do and you attack, you'll get excommed. They can beat up on you though. The Pope likes underdogs.

[Del Arroyo]

Also, if they're landing troops and you think your shores are guarded-- is EVERY portion of the shore guarded? Because there are alot of provinces which can be accessed from a various sea zones, even if it's only a small sliver of the shore.

DA

[King Henry V]

What I meant by guarded is have enough troops to ward off or defend my provinces from invasion.

[Ludens]

The Pope tends to tolerate small Catholic Factions attacking large ones, but not the other way round. This is indeed carried to the point of madness when it comes to reconquering lost ground or attacking in sea battles, but there it is. It is not the only way the computer cheats.

However, I have never seen cheating naval invasions. I don't know how BKB's map looks, but if it is like the vanilla M:TW map, one ship in the Gulf of Lions ought to have prevented it. They could have used a line of ships along North-Africa to invade.

[King Henry V]

The seas in BKB are exactly the same as in vanilla, and the next trun I checked to see wether they did indeed have any ships along North Africa, but they only had one of Algeria.
Some new updates:
I can't launch a Crusade against Constantinople, because the Byzantines are allies of the Pope. I have no allies, even those who are not allied with my enemies do not want to ally themsleves with me. Then unexpectidly, without even being excommunicated, the Pope sent its troops to attack me in Naples! I managed to beat them off (I thought for a moment wether even resisting His Holiness would get excommed), but decided not to invade the Papal States and Rome as the last thing I need now are a bunch of angry, devout peasants revolting in Brittany and Anjou. Fortunately, I have managed to build a fleet of caravels (only saving them by sending them into the Central Med, where the Byzantine ships can't get me) and pretty much destroyed the Med fleet of the Byzantine Navy. The Danes, on the other hand, still blockade my Channel ports.