https://en.wikipedia.org/wiki/World_of_Warcraft:_Legion - Legion - August 30th 2016
https://wow.gamepedia.com/Patch_7.1....2014%2C%202016. - 7.1 - October 25th 2016 - Just under 2 months
https://en.wikipedia.org/wiki/World_...le_for_Azeroth - BfA August 14th 2018
https://wow.gamepedia.com/Patch_8.1.0 - 8.1 - December 11th - just under 4 months
Apparently fact checking is harder than you make it out to be