Dun Modr is a fortified middle-sized dwarven town that sits along the road just south of Thandol Span, ruins of the ancient dwarven city of Dun Modr also lie to the north of the bridge as well. The fallen city of Dun Modr is located in the north of the Wetlands. It is occupied by Dark Iron dwarves. They claim the fallen dwarven city, as their own. The Dark Irons kill anything that enters their territory — including undead.
Dun Modr has traditionally been of major strategic importance for controlling the region. During the Second War, a major battle was fought to retake Dun Modr from the Horde. An orcish outpost was nestled near the ruins of the ancient dwarven city of Dun Modr. It was a vital staging area for Horde troops. It had repeatedly beaten back Alliance troops and ravaged the surrounding farmlands. Forces striking from Tol Barad launched an attack on the outpost. The taskforce of Stromgarde warriors laid siege to Dun Modr and captured it. They were able to force the orcs to retreat across the Thandol Valley to a secondary outpost at Dun Algaz. The Horde forces made a counter attack retaking Dun Modr, and bringing forces to bear against Stromgarde's island citadel of Tol Barad. While they may have initially retaken the city, ultimately the attack not successful. The Alliance held the ruins after the war, attacking the remaining orcs in the region.
While dwarven soldiers gave their lives in far off territories in the name of the Alliance, the dwarven lands fell prey to the evil deeds of the Dark Iron dwarves. They laid waste to the Thandol Span, and southern Dun Modr fell soon after.
There are some quests that can be taken from the outskirts of Dun Modr that involve killing the Dark Irons. Other quests involve the guardpost at the center of the Span (the entrances on either side of the span), and just over the Span into Arathi Highlands to the east of the Span. It is believed the Dark Irons are led by powerful warlock, Balgaras the Foul.
This section concerns content exclusive to Cataclysm.
In the Cataclysm it is revealed that the Dwarves at Dun Modr are, in fact, loyal members of the Twilight Cult. Dun Modr now has a new Alliance flight path, and in the hills far above is what appears to be a crashed zeppelin (it should be noted that said zeppelin has existed since the release of World of Warcraft).