Tacitus Annals - Horse-bowmen

[dadlamassu]

I have a question but am not sure if this has been discussed already or if this should be in the "Allies and Enemies" section.  

Tacitus Annals 2.16 mentions that: 

Our army advanced in the following order. The auxiliary Gauls and Germans were in the van, then the foot-archers, after them, four legions and Caesar himself with two praetorian cohorts and some picked cavalry. Next came as many other legions, and light-armed troops with horse-bowmen, and the remaining cohorts of the allies. The men were quite ready and prepared to form in line of battle according to their marching order.

The Question - who were these horse-bowmen, how many, how were they equipped and how were they dressed?  

Many thanks

[Nathan Ross]

who were these horse-bowmen, how many, how were they equipped and how were they dressed? 

Tacitus is often a bit vague with his military details, so I don't think we can be sure. The phrase he uses is levis armatura cum equite sagittario, which is not too informative.

Since he's previously listed the auxiliary Gauls and Germans (auxiliares Galli Germanique) and later adds the remaining cohorts of the allies (ceteraeque sociorum cohortes), the text implies that these horse archers were something different. My guess would be that these 'auxiliaries' and 'cohorts of allies' were not regular auxiliary cohorts of the post-Claudian type, but more irregular formations raised locally.

So the equites sagittario might just be irregular mounted troops armed with bows, but could perhaps have been something like the later auxiliary horse archers, of the cohors equitata sagittaria perhaps. Most of the latter appear to have had their origin in the east, however.

One clue might be the inscription CIL 09, 03664, from Italy, which mentions a praefecto sagittariorum qui militaverunt sub Germanico Caesare in Germania (?) who later (?) served as praefecto cohortis Ascalonitanae - the latter would presumably be an eastern auxiliary cohort, so perhaps the archers were too?

[dadlamassu]

who were these horse-bowmen, how many, how were they equipped and how were they dressed? 

Tacitus is often a bit vague with his military details, so I don't think we can be sure. The phrase he uses is levis armatura cum equite sagittario, which is not too informative.

Since he's previously listed the auxiliary Gauls and Germans (auxiliares Galli Germanique) and later adds the remaining cohorts of the allies (ceteraeque sociorum cohortes), the text implies that these horse archers were something different. My guess would be that these 'auxiliaries' and 'cohorts of allies' were not regular auxiliary cohorts of the post-Claudian type, but more irregular formations raised locally.

So the equites sagittario might just be irregular mounted troops armed with bows, but could perhaps have been something like the later auxiliary horse archers, of the cohors equitata sagittaria perhaps. Most of the latter appear to have had their origin in the east, however.

One clue might be the inscription CIL 09, 03664, from Italy, which mentions a praefecto sagittariorum qui militaverunt sub Germanico Caesare in Germania (?) who later (?) served as praefecto cohortis Ascalonitanae - the latter would presumably be an eastern auxiliary cohort, so perhaps the archers were too?

Please accept apologies for delay in responding and many thanks for your helpful answer.  I asked because I was thinking of adding them to my wargames collection so now I have an excuse to raise up to 3 new units:
1. Locally raised mounted bowmen
2. Allied Irregular Eastern horse archers 
3. Mixed Auxiliary (light?) infantry and cavalry unit again of Eastern origin.
Thanks again

[Sean Manning]

Another way of reading the passage would be that Tacitus sees "bearers of spear and shield" as the default, unmarked type of troop (to be described as legions or by ethnicity) while troops without spears and large shields, such as bowmen and horsebowmen and "light armed", are described by their way of fighting.

David W. McAllister wrote a MA thesis on imperial Roman horse archers https://dx.doi.org/10.14288/1.0058215

[dadlamassu]

Another way of reading the passage would be that Tacitus sees "bearers of spear and shield" as the default, unmarked type of troop (to be described as legions or by ethnicity) while troops without spears and large shields, such as bowmen and horsebowmen and "light armed", are described by their way of fighting.

David W. McAllister wrote a MA thesis on imperial Roman horse archers https://dx.doi.org/10.14288/1.0058215

Many thanks - very useful.  The thesis identifies the unit in the German campaign as Cohors I Flavia Damascenorum Milliara Equitata.  
Still reading the thesis.
Would I be correct in taking from this that it was a mixed unit of both foot and mounted troops?