 Complete the following phrase:  The mid-3rd century saw the empire plunged into a military and economic crisis which almost resulted in its disintegration. It consisted of a series of military catastrophes in 251271 when Gaul, the Alpine regions and Italy, the Balkans and the East were overrun by Alamanni, Sarmatians, Goths and Persians. At the same time, the Roman army was struggling with the effects of a devastating pandemic, now thought to have been smallpox, the 