Of all the games I've played, the AI has only declared war on me 1 time. I thought it might be because I played at prince level but I just played and beat my first diety today with a science victory. I was next door neighbors to Assyria and Greece and the Zulu and the Huns were on the other continent so I was sure I was going to be getting into some fights but nope. I don't build big armies unless I'm doing domination, usually just 6 or 7 high tech units.
I haven't experienced this at all.
Started an Immortal game as Poland. Had a vast stretch plains to myself. Expanded widely. Used oligarchy to keep cities garrisoned. Austria was a distant neighbor and in their usual fashion did not attempt to expand past a few cities. Without open borders I couldn't get past her to see what lay beyond, so it was quite a surprise to see her capital suddenly turn that unmistakable Zulu hue. Shaka didn't get the memo that there was no war in BNW.
He wiped her out utterly. I sat four musketmen, four xbows, and four winged hussars at the mountain passes that separated our lands. Figured that with all these folks on CFC going on about a shuffle dance, that he would be all bark and no bite when he saw I had a welcoming committee ready.
Not so. Beaucoup bite. Quite nonchallantly, he marched a horde of impi with cannons and bows at the rear right up and around my welcoming committee, enveloped them and promptly declared war. 16 strength impi do amazingly well against 24 strength musketment fortified in the hills and even 28 strength winged hussars. Of course, his ultimate advantage is sheer numbers and disposability. Killed several experienced units before I fully grasped the extent of this not-so-feeble threat amd pulled back closer to my cities, making them come through the mountain passes. Brought in all the garrisoned xbows.
His peace offer was generous. I only had to give up three cities. Nearly done researching rifling. I suspect after I finish upgrades there will be a fixing of little red wagons.
Most noteworthy part was that I had five caravans going into his cities, and that still didn't bribe him into docility.
No war in BNW? Well, maybe not in the first 30 turns.