Hadrian died in 138 AD, leaving the empire to Titus Aurelius Fulvus
Boionius Arrius Antoninus, later known as Antoninus Pius. Antoninus
proved to be a strong and just leader, responsible for many
improvements within the city of Rome and it's territories, although
he achieved relatively few military accomplishments. What he did
accomplish was the enlargement and strengthening of Upper Germany, as
well as the construction of the "Antonine Wall", a
fortified turf wall some distance north of Hadrian's Wall. This wall
was abandoned around 165 AD however, four years after Antoninus'
peaceful death in 161 AD.
Marcus Annius Verus, better known as Marcus Aurelius, received the
empire, and was destined to see more battle than his predecessor had.
In 162 AD Parthia once again attempted to claim control over Armenia,
and Marcus was forced to intervene. In 166 Parthia's armies finally
succumbed to the Romans, and Parthia surrendered it's claims to
Armenia and Mesopotamia. With this victory, Rome once again withdrew
from Mesopotamia. That same year the Germanic tribes north of the
Danube began to revolt against Rome. Marcus Aurelius, as well as his
co-ruler Lucius Ceionius Commodus, brought troops to the region in
167 AD. Although the emperors were able to leave the front the next
year, the war their raged on until 175 AD, the year Lucius died. The
lands gained from these wars against the Quadi and Marcomanni were
withdrawn from once again in 180 AD.
Marcus Aurelius died that year, leaving the empire to his son Marcus
Aurelius Commodus Antoninus. Commodus was the death of the relative
peace and prosperity the Empire had been achieving. He was only 19
when he gained the title of Emperor, and his lack of wisdom and
discipline were crushing blows to the empire. He made peace with the
barbarians to the north, revealing the loss of Rome's legendary
strength and discipline. He then retreated to Rome and succumbed to a
lifestyle much like Nero's had been. Commodus was killed in 192 AD,
leaving the empire vulnerable to the civil wars that had ravaged it
in the past.