Dimachae

[Jim Webster]

, assuming only that the quartermasters could rustle up 300 pairs of riding-boots in a hurry; the only other change in equipment is that he's left his cuirass and greaves off.)

This does present an interesting question, just what did armies carry in the way of spares. We know at least one Roman Republican army had enough spare shields to produce pseudo triarii.
I'd assume that given the importance of some pieces of kit, boots, shields, spears/javelins, they'd be carried.

[Patrick Waterson]

There is also the question of what it takes to create an effective mounted soldier, and this would seem to require more than just leaving off the greaves and sandals and donning a pair of boots (which might incidentally be a reason for a possible hypaspist to be wearing these on the Alexander sarcophagus: after, all, who hunts while wearing greaves?).

If anyone unaccustomed to riding has undertaken a long, hard ride for any length of time (e.g. in pursuit of an escaping Achaemenid monarch, or for less exalted cross-country purposes) they will be aware that at the end of the process the rider is sore in places which prevent his effectual functioning as an infantryman.  Posture and harmony with the horse's motion are important, and require familiarity (a common Napoleonic Russian cavalryman's insult concerning a mounted infantryman was: "A dog astride a fence.")

This is one reason I am inclined to consider the dimachae as cavalry with dismounted fighting capability rather than either infantry trained to fight mounted or infantry mounted without training in mounted combat.  Diodorus' dimachae are described thus:

"Able as they are to fight in two styles, they first carry on the contest on horseback, and when they have defeated the cavalry they dismount, and assuming the rôle of foot-soldiers they put up marvellous battles." - Diodorus V.33.5
(dimakhai d' ontes, epeidan apo tōn hippōn agōnisamenoi nikēsōsi, katapēdōntes kai tēn tōn pezōn taxin metalambanontes thaumastas poiountai makhas.)

Curtius simply states:

"But rest was necessary for his wearied men, therefore to 6,000 elite horsemen he added 300 of the troops called dimachae.  These carried heavier armour on their backs but rode on horses; when the occasion and situation demanded, they fought on foot." - V.13.8
(Sed fatigatis necessaria quies erat: itaque delectis equitum vi milibus CCC, quos dimachas appellabant, adiungit. Dorso hi graviora anna portabant, ceterum equis vehebantur: cum res locusque posceret, pedestris acies erant.)

As Duncan observes, Curtius' dimachae are not specified as cavalry, though the implication is that they are such: cavalrymen with foot-fighting armour and capability.  Unlike Arrian, Curtius says nothing about cavalrymen being dismounted to provide mounts for infantrymen, and practically implies that the dimachae are an already-existing unit.

One may note in passing that 300 was a traditional strength for Alexander's cavalry units such as Paeonians and the Ile Basilike (Royal Guard Companions).

Comparing Curtius' and Arrian's accounts shows that Alexander added the dimachae before the day he dismounted 500 cavalry to mount the 500 'officers of the infantry and others'.  1) Curtius has him learn the situation from Bagistanes, reach the village where Bessus deposed Darius, catch Darius' interpreter, confirm Darius' deposition and arrange his pursuit contingent of 6,000 cavalry and 300 dimachae.  2) Then Orsines and Mithracenes arrive and detail a short-cut, so at evening Alex sets out with 'a lightly-burdened troop of horsemen' (cum expedita equitum), ordering the phalanx to follow with all possible speed.  3) 300 stadia later, he meets 'Brochubelus' (probably Antibelus), son of Mazaeus, who tells him Bessus and Darius are 200 stadia distant.  4) He pursues and comes up with Bessus' disorderly army, whereupon Bessus murders Darius and flees.

Arrian has him 1) learn the situation from Bagistanes and Antibelus, take the companions, Prodromoi and his 'toughest and nimblest infantry' (tōn pezōn tous eurōstotatous te kai kouphotatous) and reach the said village, where he confirms Darius' deposition from an unspecified source and continues the pursuit with what he has (Companions, Prodromoi and the toughest/nimblest infantry).  2) He enquires about and learns of a short cut, and realising that the pace would be too much for his infantry, he mounts 500 of the best by dismounting 500 of his cavalry.  3) and 4) He pursues, comes up with Bessus' straggling army, whereupon Bessus murders Darius and flees.

Close comparison of these accounts disqualifies the 500 mounted infantry as possible dimachae (Curtius has the dimachae added at 1) while Arrian's infantry are not mounted until 2), following the disclosure of the short cut, but also introduces a new and hitherto unsuspected dimachae candidate (embarrassingly for my earlier assumption, Arrian does not mention hippakontistai at this juncture).

The new and overlooked candidate is actually fairly obvious in retrospect: the Prodromoi.

300 is a familiar prodromoi unit size; the prodromoi are also known interchangeably as sarissophoroi, which associates them with an infantry-type weapon; a scouting role would mean that like Xenophon's cavalry (in his Cavalry Commander) they would have to be prepared to dismount for certain activities; they are also about the only contingent left in Alex's pursuit force which we have not so far considered.

[Patrick Waterson]

... a scouting role would mean that like Xenophon's cavalry (in his Cavalry Commander) they would have to be prepared to dismount for certain activities ...

Actually Xenophon does not specify that cavalry should dismount for the activities I envisaged, namely raids and ambushes; he is keen on cavalry operating with infantry in fights against opposing cavalry, but that is another matter.

This does present an interesting question, just what did armies carry in the way of spares. We know at least one Roman Republican army had enough spare shields to produce pseudo triarii.
I'd assume that given the importance of some pieces of kit, boots, shields, spears/javelins, they'd be carried.

Xenophon, Cavalry Commander 8.4, has this recommendation:

"And since bits and saddle-cloths are fastened with straps, a cavalry leader must never be short of them, for at a trifling expense he will make men in difficulties efficient."

[valentinianvictor]

, assuming only that the quartermasters could rustle up 300 pairs of riding-boots in a hurry; the only other change in equipment is that he's left his cuirass and greaves off.)

This does present an interesting question, just what did armies carry in the way of spares. We know at least one Roman Republican army had enough spare shields to produce pseudo triarii.
I'd assume that given the importance of some pieces of kit, boots, shields, spears/javelins, they'd be carried.

Didn't Roman marching armies have most of their equipment on baggage animals and carts? The infantry may well have marched with the bare minimum of equipment such as a shield, spear/pilum/javelin, sword and perhaps a helmet, the rest being on the animals/carts.

[Duncan Head]

Close comparison of these accounts ...

... is probably a waste of time given that they come from such different source-traditions?

[Erpingham]

Didn't Roman marching armies have most of their equipment on baggage animals and carts? The infantry may well have marched with the bare minimum of equipment such as a shield, spear/pilum/javelin, sword and perhaps a helmet, the rest being on the animals/carts.

Marius' mules?  Or is that just old soldiers moaning?

[Patrick Waterson]

Close comparison of these accounts ...

... is probably a waste of time given that they come from such different source-traditions?

Well, it was the technique initially employed by my esteemed interlocutor.  I do but follow in the footsteps of the master.

Didn't Roman marching armies have most of their equipment on baggage animals and carts? The infantry may well have marched with the bare minimum of equipment such as a shield, spear/pilum/javelin, sword and perhaps a helmet, the rest being on the animals/carts.

Marius' mules?  Or is that just old soldiers moaning?

Marius made his soldiery carry their own baggage.  This apparently was in the long and general run of events the exception rather than the rule; the norm seems to have been that a solider carried his own kit (including shield, helmet, weaponry and 'entrenching tool') while on the march - and often also a couple of stakes for the nightly palisade - but tents and cooking utensils would follow in the baggage train.  Rations are more of a question-mark, the obvious distribution being that the marching soldier would carry one day's food while the baggage train would have a week or so (when full).

During the Empire, a unit would march either with the usual load or as expediti, i.e. carrying a bare minimum of equipment basically limited to armour and weapons.  No stakes, no entrenching tools, just armour, helmet, pila (or later Empire equivalent), sword, shield and dagger.  (This is actually my best guess rather than a clear source statement so I would avoid quoting it as fact, simply as logical likelihood.)

Such at any rate seems to be the general pattern.  Late Empire soldiers had it easy compared to their Early Empire brethren: they seem to have carried their armour (if any) and weaponry but otherwise let the baggage train take the strain.  By the time of the Byzantine Empire even armour was being carried in the baggage, but Byzantine armies had a more extensive scouting system so the need for infantry to don armour in a hurry rarely arose.