So this is quite strange. I'm in a game where I have managed to get a vassal. After a bit I moved my units towards another civilization but once I declare war on him my vassal suddenly declares war on me. There are no alliances or anything, my vassal and the civ I declared war on haven't even met each other.

The civ I declared war on is a vassal to another player, so I did expect his liege to declare war on me. But my own vassal seems to be a bug.

Quite frankly I think this bug is about it for me. I am soooo frustrated by the stupid war system and now this. I think I might just go back to civ...