Hi, sorry if this is a noobish question, but something weird happened to me while playing a Marathon Noble game of BTS...

I was playing Vikings with five rival civs remaining: Suleiman, Hammurabi, Rameses, the Maya guy and Roosevelt. Mayans and Americans were the weakest, and I was at war with them. For the others, the diplo status was mostly Cautious or better, so I wasn't expecting any trouble...

All of a sudden while I'm fighting the Americans, the other 3 civs declare war on me without explanation - the diplo status didn't even change I think, and I didn't get that taunt that comes with a declaration of war.

Luckily I'm fairly ahead in tech so I can manage them with rifles/cavalry, but I'd like to know what could have caused the sudden world war!

Apostolic palace vote?

Sounds like the Apostolic Palace called a holy war against you.

Wouldn't I have received some sort of message if it was the Apostolic Palace?

Also, it can happen even if they don't all share the same state religion? (sorry, I'm new to this Apostolic Palace thingy)

Oh, also if it was the Apostolic Palace, would I have been able to prevent it somehow? I was never called to vote so I guess it's not for a religion I have?

You said they were cautious with you when the DOW happened? Cautious doesn't mean you're safe at all. There's a number of things that could have happened.
1) AP vote as mentioned above.
2) Multiple people were bribed into war. If you're against a religious block, it's likely that they're all buddy buddy and hate you.
3) Someone you were at war with became a voluntary vassal, causing the owner of the vassal to DOW you.
4) The other civs saw your power and decided to jump in on the scraps. Granted the AI isn't the smartest at all times ;) But they could have estimated that with 3-4 people at war with you, it might be worth it to fight for the scraps of your leftover empire. ( If the AI sees 4 people at war with you, their combined power is probably way above yours, even though a tech advantage can make this number misleading).

Actually I forgot to mention - they weren't buddy buddy at all...Suleiman declared war on Hammurabi a few turns after declaring on me!

Did they share the same religion, with you having a different one? As everyone's saying it sounds like a "war against the heathens".

You can look under the Victory Conditions tab to see what religion the AP is, and who is a member. If its in a religion that everyone else has (not necessarily the one they are in, but they have a city with it) then you wont see the vote, the leader will call for it (war against the Heathens) and if it passes, they all automatically DoW, regardless of how they voted (unless they voted to "Defy the resolution").

You should always be aware of the AP being built and what religion it is. It can suck to suddenly be told the game is over, you lost, and not even have seen it coming.

You should always be aware of the AP being built and what religion it is. It can suck to suddenly be told the game is over, you lost, and not even have seen it coming.

They can't get a diplomatic victory unless every civ in the world has the religion, i.e. is a voting member. So you can't instantly lose the game unless you and everyone else takes part in the vote.

It is possible to lose instantly after it spread to you though...although if you are looking out for it it CAN be prevented.

Also, AIs actually have a dogpile mechanic (more likely to war with civs at war, varying by leader personality but more likely for virtually all then declaring on a civ that isn't warring). On top of this, the AI factors in your power rating against its own AND all other AIs you are at war with, so it will see itself as MUCH stronger if you're at war and therefore usually has enough "power rating" to attack via backstab, even if it wouldn't normally.

What happened here was likely a chain-war-bribe vs a player vs too low power rating, or an AP resolution, and if you look carefully you can probably guess.