186 The Imperial Government
tacticalplanningasopposedtosubsequentrepresentationsoftheterrainof
campaigns.^113
Theclearestexampleofthelatterisprovidedbythesitus depicti(maps?)
whichCorbulosentbackfromtheCaucasus,andwhichaccordingtoPliny
theEldermisdescribedtheCaucasianGates(thePassofDariel)asthe‘‘Cas-
pian Gates.’’^114 Pliny’sNatural Historyindeed lists a number of occasions
onwhichincreasedgeographicalknowledgehadresultedfromratherthan
preceded military operations. Thus Aelius Gallus’ Arabian expedition—
precisely a case where routes and distances hadnotbeen explored in ad-
vance—producedareportonthepopulationandeconomyofArabiaFelix
(6,160–61);theBalticwasfirstexploredbyaRomanfleetunderAugustus
(2,167);SuetoniusPaulinusreportedontheAtlasregionandbeyondafterhis
operationsin41/2(5,11–15);andCorbuloandLiciniusMucianusmanaged
toproducedivergentviewsonthesourceoftheEuphrates(5,83).
Ofcoursewehaveanumberofgeographicalandethnographicaldescrip-
tionsoflargeareasbeyondtheEmpire,forinstance,StraboonGermany,^115
Pliny the Elderon the Parthian Empire,^116 Ammianus on the Persian Em-
pire^117 or,perhapsthemostsignificantofall,Tacitus’Germania.Itsimpor-
tance for us lies in the combination of its relevance to military relations
betweentheEmpireandtheGermantribes(‘‘solongistheconquestofGer-
mania taking,’’ 37, 2) with its dependence on earlier literary sources, only
occasionallysupplementedbycontemporaryepisodes(8:Veleda;29:theagri
decumates; 33: massacre of Bructeri; 37: recent campaigns). Indeed all the
writersmentioneddependedonliterarysourcesofvaryingdates:Plinyfinds
itnecessarytoexplainthatwhathesaysoncentralAsiawilldifferfromwhat
hasbeensaidbyearlierwriters,sincehehasgainedinformation‘‘fromthere-
centoperationsconductedbyDomitiusCorbuloandfromkingssentthence
assuppliantsorroyalchildrenashostages.’’^118
In default of any formal archives relating to external policy, for which
we have no specific evidence at all,orof an active pursuit of intelligence,
- ThisconclusionseemstometoemergefromthesurveybyR.K.Sherk,‘‘Roman
GeographicalExplorationandMilitaryMaps,’’ANRWII.1(1974),534.Notealsothesugges-
tionbyRivetandSmith(n.105),196–97,thatforNorthBritaintheRavennaCosmographer
wasusingamapwithethnicandplacenamesrevisedasaresultofSeverus’campaignsof
208–11. - Pliny,NH6,40.
115.Geog.7,1,2–3,1(290–95).
116.NH6,112–41. - 23,6.
118.NH6,23.