Ironmarch

The Ironmarch (or the Ironmarch Vanguard and Iron March) is an expeditionary force of the Iron Horde that has traveled through the Dark Portal in order to invade Azeroth, acting upon the orders of Garrosh Hellscream to establish their presence within Blackrock Spire to create a weapon of mass destruction, capable of destroying large portions of Eastern Kingdoms, including Stormwind. They have taken control of Nethergarde Keep and Dreadmaul Hold, and have allied themselves with the Dreadmaul tribe and the nefarious alchemist Kyrak. The joined force of the Ironmarch and Dragonmaw clan in the Spire is known as Black Iron.

The Ironmarch first appeared during the Iron Horde Incursion world event, immediately preceding Warlords of Draenor.

Unnamed

 * Orcs

🇨🇴 🇨🇴 🇨🇴 🇨🇴
 * Ogres
 * Dreadmaul Crusher
 * Dreadmaul Destroyer
 * Ironmarch Gundriver
 * Dreadmaul Packmaster
 * Elementals
 * Ironmarch Earth Spirit
 * Ironmarch Forge Spirit
 * Mechanicals
 * Ironmarch Bomb
 * Iron Demolisher
 * Ironmarch Land Mine
 * Others
 * Ironmarch War Banner
 * Ironmarch War Wolf

Beta mobs
These Iron Horde mobs located at the Dreadmaul Post and the Dark Portal didn't make it to live for the event. The reason for this is unknown.    

 
 * Doomfang
 * Ironmarch Line-Breaker
 * Ironmarch Felbreaker
 * Ironmarch War Engine Pilot

Trivia

 * Internally, the Reins of the Kor'kron War Wolf uses the ID named Ironmarch Warmaw.
 * An unreleased bonus objective quest in and unused strings suggest that the Ironmarch army was to be the force that invaded Shadowmoon Valley before the revamp of the zone.

Speculation
Several green-skinned orcs were members of the Ironmarch during the Warlords of Draenor beta. It is likely that they were meant to members of the True Horde that joined with the Iron Horde when they began their invasion, or they could have been a part of Okril'lon Hold and switched sides during the attack. Since one of them is still wearing what looks like a Kor'kron or Warsong clan tabard, the probability of him being an Azerothian Garrosh loyalist is very likely.