The Battle of Tyran

When contact was lost with the agri-world of Tyran, few in the Imperium imagined the horror that had descended upon it. The Battle of Tyran marked mankind's first recorded engagement with the Tyranids, the vanguard of Hive Fleet Behemoth surging from the intergalactic dark beyond the galaxy's edge.

The defenders fought as men always fight, but nothing in the Imperium's long experience of war had prepared them for the swarm. Wave upon wave of chitinous horrors overwhelmed the planet's defences, and the great bio-ships in orbit drained Tyran of every scrap of biomass, leaving a lifeless husk where a garden world had thrived. There were no survivors, no glorious last stand recorded in song.

What endured was a single automated data-relay, launched by a magos before the end, carrying grainy pict-captures of the alien tide. Recovered later, this Tyran Datacore gave the Imperium its first grim glimpse of the Great Devourer, and its first warning of the hive fleets to come. The Battle of Tyran was a catastrophe, yet it purchased knowledge, and in the wars against the Tyranids, knowledge would prove more precious than a thousand worlds.