Battle of Ailinne

The Battle of Ailinne was a joint-Imperial campaign conducted by the Iron Spears Space Marine Chapter in defence of their Chapter home world of Ailinne, located in the Celtic Sector in the Segmentum Ultima. They fought alongside several cousin Adeptus Astartes Chapters, including the Broken Wings and the venerable Blood Angels, Space Wolves] and the [[w:c:warhammer40k:Imperial Fists|Imperial Fists, to defend the Iron Spears' home world against a massive invasion by the Forces of Chaos, led by the Iron Spears' mortal enemies - the vile Chaos warband known as the Void Stalkers - alongside their allies from multiple First Founding Traitor Legions.

Background
The Battle of Ailinne took place in the year 677.M39 and pitted the Iron Spears Chapter against massive Heretic army lead by the Void Stalkers (who had returned after 441 years in hiding). The Void Stalkers' army consisted of 3,000 Void Stalkers, 2,500 Word Bearers, 2,000 World Eaters, 500 Thousand Sons, and cultist soldiers "beyond number". The battle was initially largely in favor of the Iron Spears, whose Monastery was protected by void shields, auto-defenses, and a natural ring of impassible mountains with only one passage. For a time the Iron Spears were able to exact heavy casualties among the Traitors until they were betrayed by Gofraid, Chieftain of the 10th Clan-Company. During the battle, Gofraid was psychically contacted and corrupted by Elymas, Arch-Sorcerer of the Void Stalkers.

After falling to chaos, Chieftain Gofraid was responsible for disabling the fortress' automatic defense systems and opening the "Blackstair Gate", allowing the Traitors to storm Dunbairrche directly. Gofraid also aided the Heretic army in surpassing many of Dunbairrche's defenses. To make matter's worse, a "second wave" of Traitors far larger than the first arrived to assault the Fortress-Monastery. It was then that High Chieftain Garmund Mor gave the order unleash the entire Chapters Death Company (which at the time contained 107 'Grimbloods') upon the enemy. Despite the loss of the automated defenses and Gofraid's betrayal, the Iron Spears prevented the enemy from breaching the inner-most sections of the Monastery where much of the Chapter was now holed up.

In orbit, the massive Chaos fleet prevented communication between Ailinne and the rest of the Imperium. However, it would seem that the grace of the Emperor was with the Iron Spears as a small Escort ship, under the command of Sept-Leader Murchadh, managed to escape the Chaos blockade. When the Escort ship was en route to Baal, it encountered a fleet of the Broken Wings. Murchadh relayed his story to the Broken Wings Captain who agreed to aid the Iron Spears. Murchadh and the Broken Wings Captain were able to recruit a strike force comprising of many Astartes from the Broken Wings, Blood Angels, Space Wolves, and Imperial Fists. This strike force made their way to Ailinne to provide relief for the Iron Spears. The five loyalist chapters were finally able to finally drive away the traitors (including Gofraid, now known as Talexus Battlereaver). Despite successfully defending their Homeworld and Fortress-Monastery, 75% of the Iron Spears Chapter (including the Chapter Master) had perished in battle.