Near the end of the 41st Millennium, a Deathwatch Kill-team played a vital role in preventing a Tyranid invasion of Avalos, which had previously been secured by the forces of the Achilus Crusade's Orpheus Salient.
Shortly after that grisly discovery, a Hive Ship with a substantial escort arrived. The timely intervention of a small Imperial fleet, led by the Emperor's Wrath, provided the Kill-team with a means to lead a boarding action against the hive ship.
While the invasion was halted, countless xenos did make landfall. The clean-up may take generations to complete, and still might draw another hive ship to the planet.
Further Deathwatch actions will be necessary to assist in the process of eradicating the xenos intrusion.
- Deathwatch: The Achilus Assault (RPG), pp. 40, 50