When Yu Lin Bloodhawk arrived with his men, the Orcs were chasing down human villagers and slaughtering them. This Orc squad consisted of only ten Wolf Riders and one Death Knight. With more than forty Gryphon Riders, Yu Lin Bloodhawk's force would have no trouble dealing with them.
Most Orc squads were organized this way. They spread out in every direction, wreaking havoc across Tirisfal. Only when they encountered places like the harbor, where there were large numbers of people and even a few guards, did they gather nearby squads to surround and massacre everyone. They did their utmost to keep word from getting out, lest the villagers nearby flee and leave them with no one to kill the next day.
By striking in every direction, the Orcs could indeed inflict the greatest casualties in the shortest time and collect the most Soul Gem Fragments with the fewest troops. But this approach also gave Yu Lin Bloodhawk an opening.
Had events followed their historical course, Doomhammer's strategy could certainly have succeeded. But now that someone like Yu Lin Bloodhawk had appeared, breaking free of history's trajectory, things were bound to change.
This man who had escaped history's course had disrupted Doomhammer's plans, leaving him with a terrible headache. To achieve surprise, Doomhammer had traveled light. His entire force now consisted of cavalry, and even in siege warfare, he relied on the Death Knights as his main striking force.
Yu Lin Bloodhawk's sudden intervention in Tirisfal had indeed upset Doomhammer's calculations. Without enough Soul Shards, Doomhammer struggled to besiege the city, yet he did not dare withdraw recklessly.
His withdrawal would affect more than Lordaeron alone; it would influence the entire war across Azeroth. A retreat would place tremendous pressure on the main front. Soldiers there would surely think they had