Where does the yunkish slave army outside Meereen come from? I tought Dany freed all the slaves in the Yunkai and confiscated a good chunk of the Wise Masters wealth? Did she just take them by their word and didn’t check up on the slavers upholding their end of the bargain?

So this is a question I thought I had answered, but may have gotten eaten by a browser refresh or OS crash, because I can’t find it anywhere in my archives.

So where did the Yunkish army – which keep in mind, is only one part of a larger coalition which includes the forces of New Ghis, Qarth, Elyria, Tolos, and eventually Volantis – come from?

Well, a lot of them are mercenaries who the Wise Masters hired – the Company of the Cat, the Long Lances, the Second Sons, and originally the Windblown – because while Dany redistributed a part of their wealth, her terms that the slaves should be given “as much food, clothing, coin, and goods as he or she can carry” would leave the bulk untouched.

But I imagine your main question is about these soldiers:

“There were more, near as mad or worse: Lord Wobblecheeks, the Drunken Conqueror, the Beastmaster, Pudding Face, the Rabbit, the Charioteer, the Perfumed Hero. Some had twenty soldiers, some two hundred or two thousand, all slaves they had trained and equipped themselves.”

I think there are two explanations for where these slave-soldiers came from. The first is that the Yunkish simply bought them on the open market when they re-established slavery and began re-arming for war against Cleon. Certainly this explains sub-groups like the Clanker Lords.

However, this explanation doesn’t work for Yunkish commanders like the Little Pigeon and the Girl General, both of whom are described as having bred their soldiers, which requires multiple generations’ worth of time, and thus can’t have happened in the few months between Dany’s liberation of Yunkai and the second siege of Meereen.

My explanation for this latter group is that they were probably not in Yunkai when it was attacked. See, it’s rather unusual for Wise Masters to produce and train soldiers, since Astapor specializes in the Unsullied and Yunkai specializes in sex slaves. Given that they lead their soldiers in person rather than selling them to others, and that they’re ambitious for overall military command, my guess is that the Little Pigeon and the Girl General and their ilk were working as mercenaries elsewhere in Essos when Yunkai was attacked, and then came back home to take revenge on Dany.

How well organised are mercenaries in Westeros? They’re apparently not as prevalent as in Essos, and there’s the occasional mention of “freeriders”, but are there any larger companies of specialised troops, such as crossbowmen or pikemen?

Freeriders aren’t mercenaries.

Because the ruling class of Westeros relies more heavily on control of military manpower than the ruling class of Essos, it’s usually the case that mercenaries in Westeros are usually Essosi free companies who’ve been brought over as additional troops and/or specialized troops (Myrish crossbowmen, for example), whereas native Westerosi largely serve in the armies of their liege lords.

However, there is a history of Westerosi mercenary companies being founded as a way to get inconvenient fighting men out of the country following a major political rupture:

The Company of the Rose, for example, was founded by Northerners who refused to accept Torrhen Stark’s submission to Aegon the Conqueror, and preferred exile in Essos instead. Their departure for Essos meant that Torrhen wouldn’t have to deal with a large militant faction of nationalists, who might have supported his sons’ faction in Northern politics.
The Stormbreakers were founded in the wake of the Dance of the Dragons, and likely absorbed a lot of the excess soldiers who had been mobilized during the Dance and now had no peacetime employment. Based on the name, I wouldn’t be surprised if the original founders were Riverlander veterans of the Battle of the Kingsroad, but I would also guess that no small amount of their number were made up of the surplus Northmen who were left behind after the “Hour of the Wolf.”
The Second Sons predate the Conquest, which shows how long this tradition has been going on, and were formed more for economic reasons than political ones. As WOIAF tells us, the company was “founded by twoscore younger sons of noble houses who found themselves dispossessed and without prospects.”

It is important to note, though, that all of these free companies left Westeros and worked exclusively in Essos – which was probably quid-pro-quo for allowing them to be formed in the first place.

a question about the westerlands army numbers. i know the common sensus seems to be around 50-55000 men in regards to how many the westerlands can raise. this is based on how many fought in the war of the five kings. but wasnt a large portion of tywins army composed of mercenaries in addition to his levies?

Not really. The only mercenaries we see serving Tywin are the Bloody Mummers, who only number a hundred altogether, and that Tyroshi band who abandoned Jaime’s army at the Camps and promptly vanished.

I have some theories about why, but there’s no evidence on this.

Why don’t the Lannisters use their money as more of strategic advantage during the war of five kings? They hire Tyroshi sellswords and Vargo Hoat, so clearly they’re not opposed to using mercenaries. Nor is there a “code” against it in Westeros – Stannis hires Sallador Saan, and in TWOW he wants to hire the Golden Company. You’d think given his money Tywin would hire 10 or 20k sellswords and use them to fight Robb Stark. But we never hear about the Lannisters approaching the Golden Company etc.

They certainly did, but there’s a couple factors that prevented them from making full use of those resources in the phase of the War of Five Kings from the outbreak through to Blackwater:

They’re on the wrong side of the continent, and Stannis and his navy stands between them and the Narrow Sea. So getting mercenaries to their army, and for that matter getting envoys to the Free Cities, would be rather difficult.
Stannis is competing with them for mercenaries. He’s hired around 3,000 already. And mercenaries are not a fully fungible product – mercenaries might be already under contract (the Golden Company was under contract with Myr, and given the then-impending war between Tyrosh and Lys, it’s quite likely a lot of companies had already taken up contracts with them), or be in some other region of Essos where it’s harder to contact them. As the WOIAF says, “when not employed by the three quarrelsome daughters, the sellswords oft seek to carve out conquests of their own.”
The Golden Company is not really a possibility. Ser Jason Lannister died in the War of Ninepenny Kings, and Tywin, Kevan, and Tygett all fought with distinction against the Golden Company. Moreover, the Reynes and Tarbecks both fought for the Black Dragon in the First Blackfyre Rebellion, although they seemed to have reconciled with the Targaryens by the time of the Peake Uprising.
There’s a timing issue. At the outset of the conflict, Tywin wants to mobilize before everyone else to stack the odds in his favor – the same way he did in the Rains. That means attacking ASAP rather than waiting for mercenaries to go all the way around Westeros to join up with his army.

And then in the second phase, Tywin’s got the Tyrells he can call on, and a rather negative experience with mercenaries maiming his son.