Armies of Orion-89 Zeta

Charon Hive 

Charon had long had to fight to preserve its independence and this gave the was the most militarily prepared Hive. 

Although the 300 year old High Master of Charon, Dreen Charon IVth, did not take the field, both his grandson, Reelan Charon and his half brother, Uter Charon, both made their names leading the forces of the Charon Hive in battle. 

 

Charon Guard

The elite forces of Charon, as soon as the scale of attack on the Hive was known, High Master Dreen sent half his household guard to his grandson, in order to stiffen the resolve of the majority of troops.  The Charon Guard - a mechanised force well supplied with the best armour the Hive could by were by far the strongest force on the planet.  It was rumoured that they even had managed to exhort a trio of baneblades from the Adeptus Ministorum, intended for use against the TAPs: but which would prove instrumental in the war ahead.

Charon 7th

Uter Charon had been the High Commander of the Charon forces in all the recent conflicts with Eris Hive.  His favourite troops were the Charon 7th, and these were quickly mobilised and strengthened with indentured ogryns from the promethium mines. 

While Dreen Charon wheeled his armoured columns around the flank of the hive, the Charon 7th dug in for a vicious fight at the gates of the outer hab zones. 

TAPs

At first disorganised and disaffected, the forces of the TAPs were uncertain where to march, or indeed who or what to fight, as many thought that the  Xenos attacks were surrepticious attacks from the warmasters of Charon Hive.  

Eris Hive TAPs

The TAPs forces started the war with far less effective forces than Charon.  Eris Hive had traditionally maintained a light and fast force, and these were far from the hive when the war broke out performing exercises with the forces of Sedna. 
These forces attempted to take the Orax Point spaceport in order to board the transports back to their homes.
They were led by a wily old IG veteran, the septuagenarian rejuvenat, General Blasser.  

TAPs Brigade

A lightly armoured brigade commanded by Marshal Trallen of Qua Ooa, this unit was a mixed bunch with prospectors, and the mismatched units of the TAPs.
Lightly armed, low on ammunition, it seemed at first that their position was doomed.  If anyone other than Marshal Trallen had been in command, then perhaps this would have been true.  However, the veteran warrior had seen tighter squeezes than this.