The Northlands have fallen, and now only the western regions of Lordaeron stand defiant before the ultimate supremacy of the Horde. As the Orc clans prepare for their final, massive campaign against the weakening Alliance, the War Chief sends you ill tidings. . . Gul'dan and his Stormreaver clan have betrayed the Horde and coerced the Twilight's Hammer clan to set sail and search for an ancient tomb said to be buried beneath the waves. An infiltrator under the direction of Doomhammer reports that Gul'dan has indeed raised volcanic islands from the ocean floor and thus has opened a hidden vault. While it is unknown what the great Warlock has released from this tomb, the War Chief has issued this command - Destroy the renegade clans and return with the head of Gul'dan.
The battle was the result of the treachery of the Warlock Gul'dan, Chieftain of the Stormreaver clan and former leader of the then-defunct Shadow Council. Having discovered the location of the legendary Tomb of Sargeras, which was the reason for him to create the Dark Portal in the first place, Gul'dan assembled the forces loyal to him, both the Stormreaver Clan and the Twilight's Hammer clan which was leaded by his apprentice Cho'gall the Ogre-mage, and led them towards the Great Sea. Gul'dan cared little for the result of the Second War and sought only to find the tomb and take the power of Sargeras for himself.
Initially Orgrim Doomhammer had to postpone the assault on Lordaeron's Capital City ( sending a small unit led by Urok Scratcher's commander believing that Gul'dan and Cho'gall were on the islands. They successfully reached the islands; but only managed to destroy decoys. After which they returned to Lordaeron mid battle just in time to join the )battle at Dalaran, and later the battle at Lordaeron. The real Gul'dan and his followers apparently returned to the island sometime during the battle at Lordaeron ( with the massive loss of forces the warchief was forced to withdraw his troops from Capital City to deal with the traitors, he sent a large contingent of the )Blackrock troops alongside with Rend, Maim and their Black Tooth Grin clan to slaughter Gul'dan and everyone of his followers. ( )
After arriving to the sumberged Tomb of Sargeras; Gul'dan, Cho'gall, some necromancers, warlocks and Ogre-magis started raising the Tomb from the floor of the ocean. Meanwhile, Torgus had already reported to Orgrim about Gul'dan treachery and Rend was going directly to battle Gul'dan. After hours of conjures Gul'dan and his followers succeded in raise the Broken Isles, however after a few moments Rend Blackhand and his Black Tooth Grin warrior saw them and prepared for the battle.
Cho'gall detected the ships of Doomhammer's troops before they arrived the isles. The Ogre Mage and most of the troops of both clans stood there to fight, they promised to Gul'dan to make everything possible to stop the Horde, meanwhile Gul'dan with some shamans and warlocks went inside of the Tomb of Sargeras. ( )
First Urok's unit had to establish a city on the largest of the islands to the east and north. For this purpose, they sent their warships with a flier to clear the way. Two enemy ships and a submersible had to be sunk first, then a tower; finally, the inland catapult was drawn to shore with a fast destroyer and dissasembled. While the warships waited, the transports were loaded with all but sappers and peons to make a landing; soon the island was theirs. While the existing structures were removed, the transports went back for the rest of the units and brought them safely to shore. From that point it was a matter of building a city from scratch, starting with a hall as close to the mine as possible without being too close to shore. With the threat of enemy juggernaughts coming soon, all units were moved as far inland as possible and the ships were sent to anchor at the southern tip of the island.
As soon as a barracks, lumber mill, and a blacksmith had been built, they concentrated on producing catapults. These they used to sink any enemy ships foolish enough to wander too close to the shore by directing all of them to attack at once, then moving them safely back inland. Cannon towers helped somewhat, but their lack of mobility got them destroyed almost as fast as they could be built. Once they had a fair-sized group of catapults to fend off ships, construction of the shipyard and accompanying structures began on the southeast side of the island as far from enemy eyes as possible. To carry out their plan of invasion, they would need only two juggernaughts and three transports to make a landing on the main island. They loaded them with five trolls to give them a chance against flying daemons, a single worker, six ogres, and six catapults.
The flotilla was escorted by a zeppelin to spot enemy submersibles. It sailed west to the edge of the area before turning north and quietly passing the main island. Then it headed east to find a good landing spot south of a small barren island. The juggernaughts were sent in first to clear the shore of a tower and catapult before the troops were unloaded behind a small stand of trees. They were careful to unload the ogres first, with catapults behind, and trolls on the other side, since the enemies would come to them once the catapults started on the enemy barracks nearby. When things quieted down a bit, Urok's forces erected their own barracks and began pouring troops and catapults through it to slowly take over the island. Urok's unit blew a hole through some rocks with sappers and claimed both of the heads of an orc and ogre-magi (believed to be Gul'dan and Cho'gall) as a clear signal to all who would oppose the Horde. ( Urok Scratcher's unit then traveled to Dalaran to assist in the siege there. ) ( )
However, Urok's unit had only taken out decoys and the battle continued to find the real Gul'dan and Cho'Gall. During the battle both sides suffered heavy casualities but the difference were the numbers, the Stormreaver clan was the smallest of all and the Black Tooth Grin clan was one of the largest clans within the Horde, Gul'dan forces were outnumbered and they knew it, however they were fanatically loyal and refused to surrender, they fought until the last orc, they took many of Doomhammer's warriors with them. ( )
However, the truth is that Cho'Gall faked his own death, cutting one of the arms of the strongest Black Tooth Grin warriors, as he fell, while Gul'dan went inside the Tomb of Sargeras. Finally the beach was full of corpses with only Doomhammer's forces standing, meanwhile Gul'dan continued his journey inside the Tomb. He brought some shamans, necromancers, warlocks and ogre-magis with him, he frightened his warriors by killing Urluk Cloud-killer and they started to search for the powers. They found a hidden vault, protected against all Azerothian races by Aegwynn, but Gul'dan was an orc of Draenor and he could opened it. He looked for the Eye of Sargeras but only found crazed daemons that ambushed him. His warriors abandoned him when they saw the daemons, still he continued, he evaded the guardians but then he heard a laughter, Sargeras was mocking Gul'dan. Gul'dan started dying because of injuries caused by the daemons, he wrote his story in runes with his own blood. Gul'dan didn't found the power to become a living god, but death in the hands and claws of the mad demons locked within the halls of Sargeras's final resting place. ( )
Rend Blackhand commanded the troops to made an attack against Gul'dan but when they found the tomb, the demons attacked them, many were paralized by those horrible beast but others fought back and they could win the battle. ( The destiny that was suffered by Gul'dan and his forces was the same treatment that was promised to any other clans that questioned Urok commander's military prowess. ) ( )
Only a few Warlocks and Necrolytes of the Stormreaver clan, such as Drak'thul, survived.
- The Horde was left divided and weakened, thus preparing the way for the victory of the Alliance over the Horde, however now they hadn't to worry about traitors.
- Gul'dan was killed, though his Skull retained all the massive power once held by the Warlock, thus becoming an amulet of unparalleled power. The Skull was apparently taken by one of the survivors and found its way to Draenor and to the hands of Hurkan Skullsplinter of the Bonechewer Clan, who ignored the power of the Skull and wore it simply as a sign of his power.
- The corpses of the fallen Horde warriors were raised by the magics emanating from the Tomb. The undead skeletal orcs began to recreate the battle in which they fell; until Maiev Shadowsong came and wiped out the entire host of undead warriors.
- Drak'thul becomes a hermit.
- The few surviving Warlocks, Necrolytes scatter and, some hide in the Broken Isles while others reach the shores of Kalimdor. It is possible some of these survivors joined the new Shadow Council.
- The few survivors from the Twilight's Hammer clan started serving the Old Gods and recruiting members of any race.
- After Urok's unit had defeated Gul'dan and Cho'gall, they travelled to Lordaeron to assist in the destruction of Dalaran.