"The Chimeran threat began in the Zebra Empire. The origins of the creatures are currently unknown but their presence was devastating and swift. During the past decade, reports of biological experiments began leaking out of Southern Equestria. Then rumors began of ponies disappearing and villages being destroyed over night; then entire cities. At first, we thought that the zebras had developed a weapon of unparalleled power; but the truth was far worse. The Chimera stayed sealed within the Zebra Empire for several years, but in 1949, the Chimera launched an offensive attack that overwhelmed all of Equestria in a matter of weeks. For several months we thought Canterlot was safe, but in September of 1950, they attacked Canterlot. Princess Celestia had prepared for them, but in only a handful of months, the war was lost. The surviving ponies abandoned the cities and villages to the Chimera and settle in military outposts and stables. the Chimera had won."
"On July the 12th, 1951, the United States and British military launched an assault on the Equestrian city of Vanhoover. On the second wave of that assault was a human US Army Ranger Sergeant named Nathan Hale. The actions of that soldier are a matter of both scrutiny and myth. What follows are the known events between July the 12th and July the 14th, the day he was last seen."