From WoWWiki

The only Alliance outpost in Durotar, Tiragarde Keep is manned by soldiers loyal to Admiral Daelin Proudmoore. Since Daelin’s death, they have continued their crusade against the Horde. While Jaina Proudmoore does not approve of their actions, the majority of the Alliance accepts the dangerous philosophy of these troops. They are almost as fanatical and determined as the Scarlet Crusade. It's believed that Thrall hasn’t sent troops to attack the outpost out of mercy, and that may prove a strategic mistake.^{LoM 35} The small fortress is home to about 200 Kul Tiras soldiers.

Despite the peace agreement founded by Warchief Thrall representing the orcs and Lady Proudmoore representing the humans, both races retained underlying suspicions of the other. There were even those who continued to hold onto old hatreds. One particular human, who also happened to be the father of Jaina, led his naval fleet from Kul Tiras to the shores of Durotar. There, Admiral Proudmoore hastily constructed Tiragarde in a glaring violation of the treaty. This one event is said to have started a domino effect that led to the breaking-down of relations between the Alliance and the Horde that we all struggle through today.

Though Jaina was forced to sit back and watch the orcs slay her father in battle in order to reassure them of her intention to continue honoring the peace agreement, a set of special orders written by the Admiral before his departure from Kul Tiras has recently come into effect. With no word from Proudmoore's fleet since their arrival on Kalimdor, Lieutenant Benedict and Watch Commander Zalaphil have been dispatched to retake the keep and guard it from the orcs who wish to finish tearing it down.

The damaged keep still stands today, a gleaming white structure distinctly out of place among the crimson rocks of Durotar. Benedict rules over this tiny parcel of land, and the Kul Tiras Marines and Sailors patrolling the crumbling ramparts are well-trained and filled with contempt for the Horde. A letter in an early horde quest shows that the Kul Tiras are there to finish what Daelin started, that is invade Durotar and kill all the orcs.

Subzones of Durotar

Blackblood Gorge • Bladefist Bay • Burning Blade Coven • Darkspear Strand • Deadeye Shore • The Den • Drygulch Ravine • Dustwind Cave • Echo Isles • The Great Sea • Hidden Path • Jaggedswine Farm • Kolkar Crag • Orgrimmar • Razor Hill • Razor Hill Barracks • Razormane Grounds • Razorwind Canyon • Rocktusk Farm • Scuttle Coast • Sen'jin Village • Shrine of the Dormant Flame • Skull Rock • Southfury River • Spirit Rock • Thunder Ridge • Tiragarde Keep • Tor'kren Farm • Valley of Trials