Waaagh! Grom was one of the most destructive and successful Waaagh!s ever. It was led by Grom the Paunch, a Goblin warlord. He and his army defeated the Dwarfs and invaded The Empire, vanquishing several of its armies and ravaging several of its provinces. Building a fleet, he later invaded Ulthuan, the homeland of the High Elves, where he was finally defeated by Eltharion.
The boss of the Broken Axe Tribe, a goblin tribe established at the eastern end of Mad Dog Pass, Grom's rise to fame began around 2400 IC with an eating competition. Determined to win, he ordered a course of raw Troll steaks. Troll flesh has the particularity of regenerating unless thoroughly cooked, and the flesh began to regrow inside his stomach. Amazingly Grom's stomach managed to consume the flesh as fast as it regrew and Grom gained several pounds in weight, his belly widening tremendously. He would be plagued by bouts of explosive flatulence and constant agony due to chronic indigestion for the rest of his life.
As far as Goblins and Orcs are concerned, a large boss is a powerful boss, and under that reckoning Grom was powerful indeed. During the next ten years Grom managed to unite all local Goblin tribes and subjugated the Night Goblin tribes of Thunder Mountain. It was the beginning of Waaagh! Grom.
Around 2410 IC the Goblin horde marched through Black Fire Pass heading north-east along the Worlds Edge Mountains, plundering several Dwarf tombs and destroying several of their smaller holds. A gigantic statue of Grungni was vandalised, and hacked into Grom's image. A Dwarf army intercepted the goblin horde near Karak Varn. The ensuing Battle of the Iron Gate was technically a draw with heavy losses to both sides, but Grom could afford the losses unlike the Dwarfs. Desperate, High King Bragarik sent an envoy to The Empire asking for help.
Unfortunately The Empire was ruled by the incompetent Dieter IV, who declined to send a military expedition to the aid of his ancient allies. Instead he quickly transferred the Imperial court from Nuln towards Altdorf in order to be as far as possible from the Goblin threat.
Disgusted, King Bragarik could only record the emperor's failure in the Book of Grudges, and lacking reinforcements the Dwarfs entrenched themselves in their holds. Rampaging without opposition, Waaagh! Grom was joined by several Forest Goblin tribes from the Great Forest and many Night Goblin tribes of Red Eye Mountain.
Unable to storm any of the Dwarf holds, the Goblin army turned west and invaded The Empire.
Defeating some Imperial armies en route, Grom overran and devastated Stirland, Talabecland, and Hochland. Instead of raising new armies, Dieter IV did nothing but skulk and dream of better days while the Great Forest became a virtual Goblin realm where even Imperial armies were in danger.
As the goblin horde moved westwards the countryside was all but abandoned while the people fled to the cities. Nuln, the magnificent imperial capital whose defences had long been neglected, was stormed and burned to the ground. Middenheim was besieged. Averheim managed to hold on, defended by its militia and no less than five Knightly Orders, while The Moot was thoroughly pillaged. It fell to Wilhelm III, Prince of Altdorf and Dieter's cousin, to organize the defence of the Reikland. Luckily for The Empire Wilhelm was a courageous and skilled general.
Noticing that the Goblin horde was divided in smaller armies, Wilhelm avoided the larger ones, and checked several of the smaller ones. Altdorf was saved as Grom's attention shifted towards Middenheim. Disgusted by the failure of his subordinates to take the city, Grom broke the gates himself.
Disappointed by the weak resistance, Grom only plundered the roof of a nearby temple of Ulric in order to build a large and sturdy Wolf chariot. Afterwards he led his army towards the coast, devastating Nordland. Upon arrival the goblins felled several acres of forest and began to build a massive fleet.
Upon reaching the coast, Grom ordered the construction of a massive fleet of ships, acres of forest were cut down to provide timber for the fleet, and whole tribes of Goblins was sent to forage for material amongst the ruins of the Empire. For weeks the makeshift forges bellowed and Goblins sweated as the ramshackle armada took shape. It was a fleet whose like had never been seen before, vast hulks and crudely fashioned wood propelled by massive thread wheels, gigantic ragged sails and feverishly straining Snotlings.
When Grom set sail and made his way along the coast, he was shadowed by a fleet of ships from the Empire. Admiral von Kronitze did not want to risk engaging the Goblin fleet if it could be avoided, reckoning that time, tide and greenskin naval ineptitude would do much of the work for him. Alas, as the fleets approached Marienburg, freak weather drove them into bloody battle that saw half of the Imperial navy sunk to the bottom of the sea and the rest scattered. The Goblins themselves lost dozens of ships to the storm, each crammed to the brim with greenskins. With his fleet battered Grom intended to seek fresh timber on Marienburg shoreline, but as the evening grew so did the storm. Though Grom ranted and railed at his crew they could do little overcome the awesome winds and the gargantuan greenskin fleet was blown westward.
- Warhammer Armies: Orcs & Goblins (4th Edition), pgs. 9, 10, 12, 97
- Warhammer Armies: Orcs & Goblins (7th Edition), pgs. 8, 9, 37