Strong opinions weakly held: Hydaspes

[Paralus]

I don't think its impossible that Alexander willingly faced 30,000 Indians with 13,000 of his own men. He believed he was divine, and his veterans were the best in the world at killing people and breaking things. He also had cavalry superiority, so he didn't have to worry about his infantry line being outflanked. I have no idea whether Porus' kingdom was large enough to produce an army of 30,000 though! And our accounts of the battle sound like the Indian army was much smaller.

And that last is the key: the related action shows Alexander surrounding the Indians with the “strike force” he took across initially. Whilst the narration of the action might be a little confused and elements left out, it is doubtful that all sources failed to notice other infantry units joining the battle. No source mentions any other units joining battle and so Alexander fought the battle with two taxeis of the phalanx, the agema of the hypaspists and the regular hypaspists, half or so of the hipparchies, the cavalry from Bactria, Sogdiana, and Scythia, and the mounted archers. Arrian totals these later as 5,000 horse – as you say. Arrian’s numbers for infantry do not, in any case, add up: even with 3,000 hypaspists, 3,072 phalangites and a minimum 2000 Agrianes and archers we get over 8,000. His “6,000” must apply to the “heavy” infantry only.

Other numbers are somewhat more problematical. I don’t see a reason to suppose that the taxeis of the phalanx were now 2,000 strong. There is circumstantial evidence for a seventh taxis which, if correct, might argue against enlarging the complement of the unit across the board. The general view is of 1536 per unit (16 lochoi of 256). This is what Alexander is trying to put together with the “mixed phalanx” – where the files are still sixteen deep and obviously in closed up “battle order” unless they fought in open order (funny that he didn’t think to create them as eight deep in their “normal” fighting order!) – in the absence of Antipater’s reinforcements.

The hypaspists and their agema are a perennial and impenetrable problem. There is evidence that, by this time, the corps had been expanded to four chiliarchies (Diodorus, for example, describes them as “more than 3,000 strong” in Eumenes’ army). On that basis I’d not disagree with 4,000 or so although the above infantry numbers give pause.

The light troops listed by Arrian are the Agrianes (minimum 1,000) and the “archers” (Tauron’s and also a minimum1,000). Curtius does mention “Thracians” but he may have erred as the bulk of these light troops were left in Media and Parthyaea as “satrapal” forces (Arr. 3.19.7 and 5.20.7). Arrian describes the Agrianes and archers as being posted on “the extremities of the phalanx”. He mentions the “Agrianes and javelin throwers”. We do not know who these javelin throwers are if they are not the Agrianes as they are not listed amongst the troops selected and enumerated twice.

As for Porus, Arrian relates that he had 200 elephants between which he placed his infantry – as well as infantry “outside” of the elephants (wings abutted by cavalry). He further states that the elephants were 30metres apart. This gives a line of six kilometres. If the spaces are filled by infantry that argues for rather large totals. If Macedonian “battle order” is assumed that’s a frontage of men (not counting the wings) of about 5,470. How deep were they? We don’t know.

What we do know is that Alexander's infantry – some 8,000 or so strong – are to take on the centre. After the sarissae and javelins had done their job Alexander then orders the phalanx to lock shields and press forward whilst he and the cavalry get around and behind the Indians. I find it difficult to imagine 8,000 men, in synaspismos and likely occupying no more than about 230 metres of frontage, taking on the confused Indian line as described. I have a similar difficulty with them beginning the battle taking on an Indian frontage of six kilometres with a frontage of 460 metres.

Any way you work it the infantry phalanx as given was not about to take on the Indians as described. Even at four deep the frontage is only 915 metres and 1,830. The army of Porus in this battle cannot have been 30,000-50,000. The number of elephants is grossly exaggerated and Curtius’ 85 is closer but likely too much

I do think that Plutarch is closer to the truth with his number of 20,000 infantry. Some these are deputed to watch Craterus (and those under Meleagher you'd think). This is not Darius at Guagamela with an empire to draw on. Hence Alexander, taking some 13,000, provides two feints to split Porus' forces and leaves strict instructions that they do that precise job. He then takes what is necessary to tackle what he estimates is the remaining "main" force.

Presumably Porus figured to deny Alexander a crossing of the river - diffucult enough - and thus have him head off in pursuit of easier prey. Perhaps he thought to execute a "Stirling Bridge" had Alexander initially forced a crossing. If so, he seriously misjudged his Macedonian conqueror.

All that having been said – and back to the start of this thread – I can find no room in Alexander’s dispositions for Paullus’s Illyrians and Greek mercenaries. The Illyrians are not attested by any source at this battle. Indeed they seem only to be mentioned once and that was at Guagamela (Curtius 4.13.31):

The rearmost ranks he faced away from the front, so that the circular formation could give protection to the whole army, and here were placed the Illyrians…

The battle was won by those that Arrian enumerates as the strike force which he makes plain when giving the numbers of dead and at 5.18.1:

At the same time Craterus and the other officers of Alexander’s army who had been left behind on the bank of the Hydaspes crossed the river, when they perceived that Alexander was winning a brilliant victory. These men, being fresh, followed up the pursuit instead of Alexander’s exhausted troops, and made no less a slaughter of the Indians in their retreat.

Not an Illyrian in sight…