Ulwinter

An era of significantly colder climate lasting for several decades of the fourth century of the The New Empire.
The colder climate caused famine throughout Ettrea, especially in the north and many, many people died. The Black River froze over and Sigsland was invaded by Orcs, Goblins (and worse) from Viltland. The invaders never really organised above the tribe level, and the Knights of the Black River annihilated the hordes in a campaign lasting three years.