At the advent of the Second War, Gilneas was considered one of the strongest human kingdoms, so much so that Greymane was very resistant in supporting the newly-formed Grand Alliance to battle the Orc threat, thinking Gilneas could easily fend for itself. He eventually caved and entered Gilneas into the Alliance, but argued against its existence for the duration of the Second War. After the war ended, Greymane refused to lend further resources to the Alliance, seeing no reason to keep the orcs in camps instead of, well, dead. It's rumored that Greymane was under the control of Deathwing, who at that time was masquerading as Lord Daval Prestor -- a noble who Greymane supported in his bid for rulership of the kingdom of Alterac.
At the beginning of the Third War, the Greymane Wall was constructed, cutting off all contact with the outside world, leaving Gilneas "free from the troubles of the Alliance". Even starving or injured Alliance refugees outside the wall receive no assistance from those within. The exact reason for sealing off Gilneas was unknown ... until now.
Several years ago, Brann Bronzebeard gravely stated that Gilneas might be, at best, in a state of disarray or, at worst, completely destroyed behind the wall. He fears that the naga have taken over the peninsula, but others point to the worgen threat that surrounds the kingdom as the real reason why Gilneas has gone silent.
And worgen are both the reason and result of this silence. Archmage Arugal, Dalaran resident but Gilneas patron, saw the rise of the Scourge at the beginning of the Third War and, in desperation, summoned a force he didn't fully understand to fight them off -- the feral and unruly worgen.
Ancient texts report that the worgen may have existed for a time on Kalimdor in ages long past, and even hint to their association with a shadowy druidic order, but no solid information can be found besides this. Regardless of their origin, when summoned, the creatures often cannot be controlled, reasoned with, or stood against.
Though the areas's defense against the Scourge was successful for a time, the lupine defenders soon stopped obeying Arugal and spread their curse among the population of Silverpine Forest, unheeding to the commands of their "master". Seeing that his plan had failed, Arugal went mad with grief and adopted a number of the worgen as his "children", holing himself up in the former home of Baron Silverlaine, the castle now known as Shadowfang Keep. Unchecked and uncontrolled, the worgen curse continued to spread, even into the seemingly impenetrable kingdom of Gilneas.
When Deathwing ravaged Azeroth with his Cataclysm, the Greymane Wall was shattered, exposing Gilneas for the first time in a decade. The foggy, rainy kingdom, grim and gothic in its construction and atmosphere, remains visually a great bastion of human civilization -- though the inhabitants were not so lucky.
The worgen curse had infected their residents and promptly spread throughout the kingdom unchecked for several years. Unable to leave the kingdom's walls due to the Scourge threat and unable to sail away due to the deadly, dagger-toothed reef nicknamed The Bite, the citizens of Gilneans withdrew further and further into the territory.
Even with their curse taking its toll on the citizens' sanity, the isolation from the outside world and crippling fear of the Scourge outside their walls has resulted in a kingdom on the brink of civil war. Worse, the Forsaken have realized that the former Alliance nation now has a foothold in Lordaeron -- and will do whatever it takes to keep the new Alliance from establishing a permanent base of operations there. King Genn Greymane, once and future king of Gilneas, now reaches his hand out in acceptance of his previously-maligned Alliance.