The Fires on Tanacus

As the Tau approached, what remaining Imperial Naval Forces prepared for battle. The twin orbital platforms were ready to fire soon after the xenos ships came into scanner range and fire calculations were entered and the order given to fire once they entered maximum range. What they were not ready for was range in which the Tau could fire upon them. Three new Custodian Class Battleships stopped just short of the range of the Imperial defenses and unleashed a torrent of heavy rail cannon fire into critical points in the rings structure, causing it to collapse and plummet down into Tanacus atmosphere reaping catastrophic destruction  on the delicately assembled structure that is now keeps the planet together.
 

With the destruction of the defense rings on the attacking side, the Tau Battle Fleet moved into drop ship position on Tanacus. As the fleet prepared to discharge its cargo, the remaining Kandavar Battle Fleet struck the flanks on the Tau attempting to destroy as many ships as possible before being completely destroyed.

 Even with the battle in orbit happening hundreds of Manta and Orca crafts descended upon Tanacus thousands of battlesuits jumped from their delivery craft to lay rapid assaults to vital Imperial structures and quickly destroy as many Legio Titans as possible before they could be awakened for war. Over a dozen of the new Riptide battlesuits that were so successful at Mu'Gulath Bay cleared the way for more tau reinforcement to arrive.

The opening moments of the battle saw the Imperials sorely pressed back, and only a few points  of resistance still remained. With such a killing stoke aimed at Tanacus the planet was sure to be crushed. All hope of survival was fading from the defenders and Tau watercaste began to blair their propaganda overhead from the dropships as more Tau forces were marshaled forward.

Then from out of nowhere they struck. Space Marines of the Emperors Shadow Chapter deepstriked in behind Tau gun lines, or right between an attack force ready to crush the defenders of Tanacus. Quickly what seemed like a rout of the Imperial Forces turned into a great thrust back into the heart of the enemy. Battle Barges and Strike Cruisers came on the rear side of the Tau fleet still dueling with the Imperial Navy, destroying dozens of spacecraft in their initial assault. tau reinforcements began to slow, and the battle on the surface began to turn.

Critical to the defense of the planet was the holding of the relic Macro Cannon. With the Emperors Shadow's  pressing the assault, the Cadian  876th formed a cordon around "Old Betty" as they liked to call her. Unable to fire the cannon into space for fear of damaging the allied ships there, the cannon was realigned to fire at the Tau landing zone and killing thousands in its first call to war.

When all seemed to be turning in favour of the Imperium, the worst thing happened. In the opening moments of the battle when orbital platform sections fell into the planet and broke apart one of the major grav generators holding the metal surface of Tanacus together. At first one section fell and then more begin to break apart of crumble down in to the fiery core of the planet.

The Tau were defeated and denied the planet Tanacus, but it also no longer belongs to the Imperium. Space Marine forces teleported back to their battle fleets, but billions of citizens died as they could not make it to a bulk carrier in time to escape.

With the loss of Tanacus Imperial Forces prepared to return to Kandavar when a signal was received. A Tyranid threat has re-emerged and struck Signa IV the outermost moon of Yuion. With the Tau pushing in on the Sector the timing on the Tyranid threat could not have been worse. However, this is the Time of Ending and things can always get worse.