Emperors, Frontiers, and Foreign Relations 161the new province of Mesopotamia was entrusted to an equestrian, and an
‘‘honour’’ (the status ofcolonia) given to Nisibis, eitherafter the campaign
of195,or(lessprobably)afterthatof198,inneitherofwhichDiohimself
tookpart.^3 Nonetheless,thefactthatthepassageretailsboththeauthentic
views of an emperorand a critique of them byan ex-consul mayencour-
ageustoasksomegeneralquestions:how,bywhom,andwithinwhatcon-
ceptualframeworksweretheforeignandfrontier‘‘policies’’oftheEmpire
formulated?
Weneednotdoubttheimportanceofsuchproblems.Ontheonehand
theresultsofthesepolicieshadfundamentaleffectsonthepolitical,social,
andculturalcontextswithinwhichmillionsofpeoplelived,fromthelamp-
lightersofOxyrhynchustakingtheiroathby‘‘Caesar’’in30/29b.c.;^4 tothe
peopleofDurawhofoundRomantroopsestablishedintheircityinthelate
secondcenturyandthensawitdestroyedbythePersiansinthe250s;or(in
Ammianus’marvellousdescription)theinhabitantsofNisibisevacuatingthe
cityin363underthetermsofJovian’streatywithShapurII.^5 Ontheother
handtheproblemsinvolvetheextentofthegeographicalandethnographi-
calknowledgeavailabletotheemperorsandtheiradvisers;thenatureofthe
conceptualframeworkwhichtheycouldapplytothisknowledge;andtheir
conceptionoftheEmpireitself—either(toputitatitssimplest)asanoffen-
sivesystemdesignedforfurtherconquests,orasanessentiallystaticdefensive
system.Thentherearemorespecificandconcretebutequallyfundamental
questions.Was(forinstance)amapoftheGermanorTripolitanianfrontier,
orofnorthernBritain,availableinRome,orwherevertheemperorwas?In
eithercasehow,withwhatdelays,andinwhatformdidshort-terminfor-
mationreachtheemperororwhoevermadedecisionsonfrontierquestions?
Whoindeedwasinvolvedinsuchdecisions,andwhatdifferencediditmake
whetherattherelevantmomenttheemperorwasinRome,inaprovince,or
oncampaignelsewhere?
These questions are, of course, prompted by E. N. Luttwak’s excellent
GrandStrategy,^6 whoseapproachistoanalysetheactualdispositionsoftroops
- Dio (n. 1); Nisibis as acolonia:Dio36,6,2.Forthebackground,seeM.G.Angeli
Bertinelli,‘‘IRomanioltrel’EufratenelIIsecolod.C(leprovincediAssiria,diMesopo-
tamiaediOsroene),’’ANRWII.9.1(1976),3;cf.D.L.Kennedy,‘‘Ti.ClaudiusSubatianus
Aquila,‘FirstPrefectofMesopotamia,’’’ZPE36(1979):255.Theexactdateofthecreation
ofthetwoprovincescannotbedetermined.
4.P. Oxy.1453Sel. Pap.II,no.327. - Ammianus25,9.
- E.N.Luttwak,The Grand Strategyof the Roman Empire from the First Centurya.d.to the
Third(1976).