Question about Vassals

[RedRalph]

Playing as Mehmed 2 and have Gandhi, Saladin and Ragnar as my vassals, I know I could lose them if they lose a certain amount of land, so am I right in thinking its in my interest to give them loads of military tech? Is there any way this can backfire?

 

[Brave Jay]

you have to be careful that their land and population do not exceed 50% of yours. I once had Mansa Musa as my vassal. He was advanced and just barely under 50 percent of my land area. He was like 64% of my population. I declared war on Saladin and he was able to capture one city which gave him over 50% and thereby granting him freedom. This forced me to declare on him all over and almost wipe him out before he capitulated again.