Antonine Plague
The Antonine Plague, 165-180 C.E.,  also known as the Plague of Galen, was an ancient pandemic, either of smallpox or measles brought back to the Roman Empire by troops returning from campaigns in the Near East.  The epidemic claimed the lives of two Roman emperors  Lucius Verus, who died in 169, and his co-regent who ruled until 180, Marcus Aurelius Antoninus, whose family name, Antoninus, was given to the epidemic.  The disease broke out again nine years later, according to the Roman historian Dio Cassius, and caused up to 2,000 deaths a day at Rome, one quarter of those infected.  Total deaths have been estimated at five million.

# History
In 166, during the epidemic, the Greek physician and writer Galen traveled from Rome to his home in Asia Minor.  He returned to Rome in 168 when summoned by the two Augusti.  Galen's observations and description of the epidemic, found in the treatise "Methodus Medendi", is brief.   He mentions fever, diarrhea, and inflammation of the pharynx, as well as a skin eruption, sometimes dry and sometimes pustular, appearing on the ninth day of the illness.  The information provided by Galen does not clearly define the nature of the disease, but scholars have generally preferred to diagnose it as smallpox.
The epidemic had drastic social and political effects throughout the Roman Empire.  Imperial forces moved east under the command of Emperor Verus when the forces of Vologases IV of Parthia attacked Armenia.  The Romans' defense of the eastern territories was hampered when large numbers of troops succumbed to the disease.  According to the 4th century Spanish writer, Paulus Orosius, many towns and villages in the Italian peninsula and the European provinces lost all their inhabitants.  As the disease swept north to the Rhine, it also infected Germanic and Gallic peoples outside the Empires borders.  For a number of years, these northern groups had pressed south in search of more lands to sustain their growing populations.  With their ranks thinned by the epidemic, Roman armies were now unable to push the tribes back.  From 167 until his death, Emperor Marcus Aurelius personally commanded legions near the Danube, trying with only partial success to control the advance of Germanic peoples across the river.  A major offensive against the Marcomanni was postponed until 169 because of a shortage of Imperial troops.
During the Germanic campaign, Marcus Aurelius also wrote his philosophical work, "Meditations". Passage IX.2 states that even the pestilence around him is less deadly than falsehood, evil behavior, and lack of true understanding. As he lay dying from the disease, Marcus uttered the words "Weep not for me; think rather of the pestilence and the deaths of so many others."

# Plague of Cyprian
In 251 to 266, at the height of a second outbreak of disease, known as the Plague of Cyprian (the bishop of Carthage), 5,000 people a day were said to be dying in Rome.  Cyprian's biographer, Pontius the deacon, wrote of the plague at Carthage:
As Jews paid with their lives during the 14th century's Black Death, so in Carthage the "Decian persecution" unleashed at the onset of the plague sought out Christian scapegoats. Fifty years later, the North African convert to Christianity Arnobius defended his new religion from pagan allegations:
Cyprian drew moralizing analogies in his sermons to the Christian community and drew a word picture of the plague's symptoms in his essay De mortalitate ("On Mortality"):
Historian William McNeill asserts that the Antonine Plague and the Plague of Cyprian were outbreaks of two different diseases, one of smallpox and one of measles, although not necessarily in that order.  The severe devastation to the European population from the two plagues may indicate that people had no previous exposure - or immunity - to either disease.