Aurelian's  death  had  cut  short  the  expedition
which  should  have  vindicated  the  majesty  of  Rome
and  restored  to  the  Empire  the  Mesopotamian
districts  still  in  Persian  hands,  and  it  was  one  of
the  objects  of  Probus  to  carry  matters  to  a  conclusion
in  this  quarter.  Diplomacy  was  first  tried,  but  this
availed  nothing,  and  Probus  returned  to  Rome  to
celebrate  a  triumph  in  A.D.  281.  In  the  following
year  he  fitted  out  an  expeditionary  force  with
which  he  planned  to  take  the  field  against  Persia  in
A.D.  283  ;  but  it  was  left  for  another  to  lead  it  against
the  enemy.  In  the  autumn  of  A.D.  282  Probus  was
at  Sirmium,  his  native  place,  when  the  discontent  of

^  It  is  not  unlikely  that  the  revolts  in  Gaul  took  place  whilst  Probus
was  in  the  East  ;  his  name  is  erased  on  several  inscriptions  found  in
the  Western  provinces.  The  chronology  of  his  reign  is,  however,  very
uncertain.
3 so        THE   RESTORATION   OF  IMPERIAL    UNITY

the  army  came  to  a  head.  The  praetorian  prefect,
M.  Aurelius  Carus,  was  proclaimed  Emperor  by  the
troops  under  his  command,  and  when  the  news
reached  the  camp  at  Sirmium,  the  soldiers,  who
resented  the  severity  of  Probus'  discipline  and
their  employment  on  drainage  works,  treacherously
murdered  their  Emperor  (October,  a.D.  282).
The  reign  of  Carus,  though  brief,  was  not  in-
glorious. He,  like  Probus,  was  of  Illyrian  origin,
and  had  two  sons,  Carinus  and  Numerianus,  whom
he  at  once  raised  to  the  rank  of  Caesars.  Leaving
Carinus  as  his  representative  in  the  West,  he  took
the  command  of  the  army  which  Probus  had
assembled  and  invaded  the  Persian  dominions.
