We don’t know exactly. Given that it’s said to be one of the richest fiefs in all of Westeros, it must be extensive.
Incidentally, this is yet another reason why the Riverlands having only 20,000 swords is iffy. If Harrenhal is that significant on a continental scale, it’s got to have more men than the Freys if somewhat less than the Hightowers b/c it doesn’t have a city associated with it. So why did Shella Whent yield Harrenhal to Tywin?
Yeah that’s been my issue with GRRM’s handling of the Riverlands as well hopefully he’ll flesh it out more later on. The Lords of the Riverlands seemed more interested in preserving their holdings from being torched so the troop numbers raised are probably way lower than they would if the whole region wasn’t being turned into a slaughter house.
As for why Lady Whent yielded Harrenhal, I had assumed that she wasn’t all quite there to be honest. With her family all dead and have been left alone to herself in Harrenhal for well over a decade her mind has probably deteriorated As Cat mentioned in her V POV. If that’s the case then she maybe didn’t even register that there was a threat at all till Tywin showed up at her doorstep with his army, and without having called up her levies she’s left with only probably a small garrison to defend a castle the size of a city.
So if we’re going by that troop estimate would you agree that Harrenhal could possibly field around 10k?
See, that still doesn’t make sense to me. Because Twin marches across the Riverlands at speed, capturing Pinkmaiden Castle, Atranta/Wayfarer’s Rest, Raventree Hall, Darry, Harrenhal, without taking a scratch. Given that he didn’t have the time to starve them out, he had to have been assaulting them. If the Riverlords were keeping their men home, those assaults should have been high-casualty affairs like we see later in the series, given the defensive advantage that castles offer. Yes, there are some exceptions, but not enough to explain why Tywin’s army is completely untouched.
I would say that Harrenhal probably has 5-6k at the least, 8k at the most, given that a lot of revenue probably gets eaten up on upkeep.
Is that taking into account that Tywin had sent marauders into the Riverlands first? The Riverlords could’ve sent their forces to chase and apprehend them and fallen into traps or quagmires, leaving the castles vulnerable. If the initial castles on the western end of the Riverlands fall so quickly, the time or awareness of the eastern Riverlords could account for their fall so quickly. From the History of the Rynes of Castamere, Tywin is favorable to blitzkrieg tactics, and given that Jaimes forces might’ve been assumed to be the main and only force of the West, the Riverlords were once again caught off guard when he came from the south with his own force.
No, that really doesn’t solve the problem. In the phase of the war we’re talking about, Tywin sent Gregor in to hit known locations at the far west of the Riverlands, and we know exactly how many men were sent after them and what happened to them – Ned sent 120 men after Gregor and they got ambushed and 80 died. The splitting up to chase the marauders doesn’t happen until after the Battles of the Green Fork and the Camps.
And the word had already gone out from Riverrun way in advance back when Tywin was marshaling his forces at Casterly Rock.
The whole point of castles is that they’re supposed to be very difficult to take even with a tiny garrison. If the explanation for the missing 20,000 Riverlanders is that they’re all staying at home, their garrisons should be even bigger and harder to shift.