The Antonine Plague of 165 to 180 AD, also known as the Plague of Galen (after Galen, the physician who described it), was the first known pandemic impacting the Roman Empire, possibly contracted and spread by soldiers who were returning from campaign in the Near East. Scholars generally believe the plague was smallpox, although measles has also been suggested. The plague may have claimed the life of the Roman emperor Lucius Verus in 169 AD, who was co-regnant with Marcus Aurelius. These two emperors had risen to the throne by virtue of being adopted by the previous emperor, Antoninus Pius, and as a result, their family name, Antoninus, has become associated with the pandemic.