All of it was written during campaigning against the Marcomanni on the Danube, while its author was away from Rome.  
Book I begins "From my grandfather Verus I learned good morals and the government of my temper."  The author wrote this "among the Quadi at the Granua."  Much of it was based on a work compiled by the historian Arrian, the Enchiridion of Epictetus.  All of it was written during campaigning against the Marcomanni on the Danube, while its author was away from Rome.  FTP, name this pinnacle of Stoicism written before AD 180 by the Roman emperor Marcus Aurelius.
Book I begins "From my grandfather Verus I learned good morals and the government of my temper."  
Meditations or Meditationes