Third Battle of Terra

The Third Battle of Terra, unofficially called the End of the Archenemy, was the final confrontation between the Imperium of Man and the forces of Chaos under Abbadon the Despoiler in 345.M43. The battle lasted for a solar week in the most vicious battle ever to be seen in the galaxy.

Loyalist forces once again won the battle and ultimately destroyed or drove off great amounts of Chaos, managing to block its influence on humanity. In a repeat of the first Siege of Terra, Abbadon was killed in the siege and his flagship Vengeful Spirit destroyed in orbit.

Pockets of resistance from Chaos Daemons and Space Marines would last for a month after, but were shortly ousted by the Death Guard and the Thousand Sons.

Preparations
Not long after the Emperor of Mankind was revived by the device of the Tree of Life, a vox-cast was received from the Black Templars, then mustered around the Eye of Terror. The Black Fleet, the largest mustering of vessels seen since the Horus Heresy, had slipped moorings and was heading straight for Terra. With them came most of the remaining Traitor Space Marines, several legions worth of Titans and an unknown number of daemons and renegade soldiers. The Black Templars had attempted to stop their advance but were ravaged and made combat-ineffective. This left the Imperium with a solar month to prepare for a third invasion of the homeworld. The Emperor ordered a mass recall of every Space Marine chapter, Navy vessel and Imperial Guard regiment available.