This act actually took place after Doomhammer had assassinated Blackhand and taken over as Warchief of the Horde. Since Durotan's wife Draka had finally produced an heir, he felt it necessary to finally bring down Gul'dan once and for all, and went to his old friend and new Warchief for support. Orgrim promised he would take action, and arranged to have Draka, Durotan and their still-unnamed child to a safe haven until they could confront Gul'dan (who, presumably, had but recently made the pact with Doomhammer that led to the creation of the Death Knights). Unfortunately, Doomhammer's men included several spies loyal to Gul'dan (since most of the Horde was still under the blood haze of the Blood of Mannoroth at this time, it's really frankly amazing that Doomhammer was able to rule as Warchief at all) and they killed Durotan and Draka in what was supposed to be their refuge, even going so far as to hack off the Frostwolf Chieftain's arms so he could not hold his son before he died.
I have to think Gul'dan came up with that idea, it's the kind of insanely cruel and evil thing he would have come up with. The infant who would become known as Thrall would have died if his cries hadn't been heard by Aedelas Blackmoore, the commandant of the nearby Durnholde Keep, where Thrall would grow up.
Now, if Blackmoore hadn't been a complete and total jackhole, the son of a general who betrayed the Alliance in the first war who grew up bitter and used alcohol to cover his own cowardice in battle, this story might well be about Thrall the heroic orc gladiator and champion of the Alliance, and orcs might be an Alliance playable race. Maybe not, it's impossible to say. However, Blackmoore was petty, resentful of always having to prove himself better than his father, and a mean drunk with delusions of grandeur. He decided to raise Thrall as a gladiator and eventually got it into his head that, since everyone thought he was going to be a traitor anyway he might as well profit by it. He planned to not only use the orc he'd named Thrall as a gladiator but also to train him to lead an orc army to ravage Stormwind. He knew he had the orc troops to do it, since he was now Commandant of the internment camps, and he knew he had a tactical genius and prodigy in young Thrall. One assumes he didn't know or didn't believe that the blood haze was a factor, proving just how intensely stupid he was, as did the fact that he treated the lynchpin of his entire plan like dirt. A better man might have treated the young orc kindly just because it was the right thing to do, a smarter man might have done so for calculated gain. But Blackmoore was mostly a drunk with a big ego and more authority than he deserved by this point, and so young Thrall became the gladiator. His only real friend growing up was a young woman named Taretha Foxton, whose mother had served as Thrall's wetnurse - it had been Taretha who realized that the young Thrall did not have teeth yet and needed to be milk fed, thus saving his life, and she came to view the little orc child as a surrogate brother.
Thrall grew to understand that his 'father' would get him killed in the arena after an eye-opening beating from the man after he lost a match against an fresh Ogre at the end of a series of nine bouts in a row. His warrior trainer, a man he only ever knew as Sergeant, basically told him to stop hoping Blackmoore would treat him like a person, and from that moment Thrall planned his escape, enlisting Taretha's help. You may have been there for it if you've run the Caverns of Time instances. Thrall escaped from Durnholde only to be recaptured (which, if you've done the escort quest, won't surprise you very much, the guy runs right into Alliance patrols like they're ice cream trucks and he's an eager six year old with some change) and sent to another internment camp, where he got a taste of what orc life was like for those peons who weren't the 'pets' of demented, alcoholic Alliance commandants. Learning the story of Gul'dan's corruption of the orcish people as well as being warned by an orc servant of the camp commander, Thrall escaped again, looking for the orc he heard about in the camp, the defiant Grom Hellscream of the Warsong Clan. He found them on the edges of Lordaeron.
Grom took Thrall in (after the young orc proved himself) and helped teach him to speak orcish, since he'd grown up among human teachers and had little grasp of it. He also told him that the ragged remains of Thrall's infant wrappings identified him as a member of the Frostwolves, and so after learning what he felt he needed to know from Grommash and the Warsongs, Thrall went looking for his clan. After a long, exhausting search, he eventually found them in Alterac. There, Drek'Thar revealed to him his true heritage as the son of the murdered Draka and Durotan, and rightful Chieftain of the Frostwolves. He also saw in Thrall aptitude for the role of the Shaman and advised him to reroll, as the Frostwolves were full up on DPS warriors. Thrall quickly found himself accepted by the tribe, even bonding with a wolf named Snowsong, and soon took up the role of the shaman under Drek'Thar's tutelage. By being able to convince the spirits that he was worthy, Thrall became the first new shaman since Gul'dan had corrupted the Horde, a sign that the orcs could earn the forgiveness of the spirits they had forsaken.
But it was Orgrim Doomhammer, not Grom or Drek'Thar, who would truly set Thrall on the path to his future as Warchief of the Horde when he came to the Frostwolf camp, disguised as a wandering orc who insulted the Frostwolves, Thrall's friend Grom and the very orcish people. Provoking the younger orc into a fight, Doomhammer was eventually defeated and only then revealed himself as the orc who had let Thrall's father, his supposedly best friend, be betrayed and murdered by his own soldiers because he'd made a deal with Gul'dan instead of just killing him.
Okay, they kind of glossed that part. Seriously, though, Doomhammer basically killed Durotan with his whole 'I must have you taken into a safe place' plan. In the unreleased Warcraft Adventures game, it was apparently Rend and Maim Blackhand who led the killers, which makes Doomhammer look even more foolish, as he has the sons of the Warchief he himself just killed take his best friend to safety. This thankfully seems to have been excised from the lore, but even so Doomhammer doesn't really come off all that well here. Nevertheless, now that Thrall has proved himself (again) by kicking his ass, Doomhammer tells Thrall he has a plan for liberating the orcs from the internment camps and asks him to be his second in command to carry it out. Thrall, being awesome, can do no less.
Thrall's role in the plan is risky... he disguises himself as just another broken down, demon addicted orc, gets himself taken into camps where he's likely to be recognized, and under the eyes of the guards he manages to use his shamanistic powers to remind the orc prisoners of who and what they were before the coming of the warlock magics. Despite Doomhammer's plan being almost entirely based on risking Thrall's life, the young shaman carries it off at three camps, and the fourth camp fell to the weapons of the rapidly growing new Horde and Thrall's new powers. At the fifth camp in the Arathi Highlands, Doomhammer's rather remarkable run of luck finally came to an end and he died stabbed in the back by a spear, his last act to insist that Thrall take up his mantle as Warchief and lead the Horde.
As leader, Thrall displayed ambition and tactical genius... the very things Blackmoore had tried to drill into him... by laying siege to Blackmoore at Durnholde Keep. He made several attempts to deal peacefully with the man who had raised him but was rebuffed, subjected to the usual alcoholic tirades, and then when he finally demanded the man's surrender was forced to endure the sight of Tarertha's severed head dropped down on him from above.
As you might imagine, this drove Thrall to storm Durnholde, track Blackmoore down to his hidden tunnel beneath the keep, and force the man into a fight for his life, going so far as to arm his opponent in order to give him a fighting chance. After Blackmoore proved he wasn't just stupid, but rather monumentally stupid by trying to recruit Thrall for his plan to conquer the Alliance after having thrown the severed head of Thrall's only childhood friend at him, Thrall finally killed the man. He then delivered an ultimatum to the remaining Alliance to free the remaining orcs at other camps or face him in battle and left with his new Horde to compose a lok'vadnod, a song honoring the heroic sacrifice of his 'sister' Taretha.
We're really only half-way through the story of Thrall, but we might as well stop here. After Elizabeth's next KYL post I'll be back, this time covering the Third War and the present day.