One November day in the year 2087, everything was normal. The very next, Ancient ships had descended from the sky and just like that, there was no normal. Not anymore. 
There were only two governments left standing, the United States and Germany. In mere minutes of news coverage, we had answers to some of mankind's greatest mysteries. They left shortly after the rise of the Egyptian armies. Not out of fear, that's for damn sure. To our best estimation, they left so we would breed, expand the population that would eventually be enslaved by them. 
The smallest Ancient that anyone has ever laid eyes on is roughly eight feet in height. The largest, about the same. They walk like we do, but that's where the similarities end. A pasty gray skin, the pupils of their eyes burning with an amber-colored pigment that helps them deal with the rays of the sun, or so we're told. Transparent skull and bones, which have been linked to their ability to heal quickly. Very quickly. 
Sometimes not quickly enough though. In other words, they die. I should know, my unit has killed more of the sky-born bastards than any other group of soldiers on Earth. -Alicia Lucard

*This is the third and final installment into the series.