This is a great concept but really needs more description. you explain whats happening but i cant visualise it. I dont know about the traitor marines, the guardsman, what the comissar looks like

Also there are parts where you could really do with linking sentences as constant full stops can increase the pace but in battle scenes it tends to simply break the flow of the piece and make it choppy and loose the effect of the action.

For example

“For Victory!” responded the Guardsmen, cheering after the Commissar had roared his chosen war cry.. Several barrages from the three Basilisks behind him, stationed above the trenches on vantage points, brought down an enemy vehicle.

To me it is disjointed and irritating to read, however thats just my opinion