Antoninus Pius was an adopted son of Hadrian. His reign was not very eventful.
There were minor incursions of the Parthians, during a battle for the succesion of the Armenian throne, under Mithridates IV into Commagene and of the Alans into Cappadocia and Armenia in ca. 140. In 142, the Votadini, Selgovae, Novantae and Damnonii were incorporated again into the Roman Empire in Britain, stretching the borders from Hadrian's Wall to the new Antonine Wall. Roman Dacia was expanded to the east of the river Olt. A small revolt took place in Mauretania between 145 and 147.
Governor Gnaeus Julius Verus of Britain had to deal with a revolt of the Brigantes between 155-157. Antoninus Pius annexed parts of Germania to the Agri Decumates in 159.