Thats exactly what genedaniels1963 just said. Fortified wines are created by adding spirit to stop the fermentation at the desired sweetness. Not just adding spirits to wine at some random point but as part of the fermentation process.
Have just gotten back into home brewing and have started with a few beers, have a mead on the go currently, and I'm looking to do some wine soon as well. When talking to my father-in-law about what I was doing I mentioned that I would need to get a couple of demijons and he went out the back...