Hive Fleet Jormungandr

Hive Fleet Jormugandr is a small tyranid Hive Fleet that arrived to the galaxy from the North East to the Ultima Segmentum. It developed its activity in between the Second and Third Tyranid War, and was destroyed around 995. M41. Its named after the norse god Loki's giant serpent, said to kill the god Thor during Ragnarok.

Arrival and strategies of Jormugandr

The first sightings of Hive Fleet Jormugandr were made in the North East area of the Ultima Segmentum. Even though it seemed that it wouldn't cause that much trouble due to its relatively small size (at least compared to Behemoth and Kraken and later Leviathan), it quickly grew thanks to attacking unprotected outpost worlds. It spreaded around the Thalassi Sector, encircling most of the planets within it.

It's strategy was more subtle than the previous two Hive Fleets: Seemingly uninterested in direct attacks at first, Jormugandr floated around space, focusing on throwing as many space debris mixed with mycetic spores as possible. These spores, containing creatures such as trygons, mawlocs and genestealers, managed to enter relatively undetected thanks to all the confusion caused by the massive rain of meteorites and space debris Jormugandr had launched. The infiltrating units then buried themselves into the ground and/or started assimilating the population into genestealer cults. The digging tyranids and the genestealer cults would often work together: the mawlocs and trygons would carve deep and complex tunnels systems to protect themselves and to reach more vuilnerable spots on the planetary defenses. The genestealers would then guide the digging units where they should go next and when to start or stop the tunneling operations. This strategy meant terrible news for the planetary authorities, most of which were not only undermanned and undertrained, but also the deep tunnels meant they could never be sure if they had destroyed all of the invasive organisms if detected. Only when the invasion of the planet was sure of their tactical superiority they would then call for the Hive Ships to arrive and consume everything.

Countermeasures against Jormugandr

After two massive tyranid invasions, the Imperium knew very well not to fuck around with them. However, at first the Imperium found themselves at the end of defeat after defeat. The loss of the forge world Megyre was specially telling, after the loss a many titans and all of the arcane weaponry stored there. The tides of war began to change when Commander Chenkov destroyed the vanguard of the Hive Fleet, stoppinf it from advancing further into imperial space. Multiple astartes chapters were dedicated to Jormugandr's destruction, including the Blood Angels and the Crimson Castellans.

The decisive blow to Jormugandr was the Battle of Black Nebula, where the Imperial Navy managed to destroy and splinter most of the Hive Fleet. Admiral Vortigern Hanroth's fleet was able to slowly but surely break the Hive Ships, thanks to space marine boarding actions (how do you board a living organism, I wonder) and a massive amount of firepower, but not before losing 3/4 of his fleet.

Effects of Hive Fleet Jormugandr

Hive Fleet Jormugandr was a hard pill to swallow for the imperial authorities. Despite its small size, it had managed to advance quite a lot before being stopped, and not at a small cost. Dozens of planets were destroyed and, most importantly, hundreds of imperial words were infected by very hard to root out genestealer invasions. This meant that constant attention was needed to erradicate possible genestealer takeovers, and when Hive Fleet Leviathan arrived to the galaxy, hundreds of this dormant units awoke and broke havoc, diverting vital resources to deal with them.