I think you've got a lot of feedback here giving you plenty to take forward. First point, nice work in keeping things clear concise. I think when looking for your next project look for repeated words - for example the first sentence has the word 'battle' twice as well as battle field, then again in the next sentence. If you use a word like that, try to not use it again for another two or three sentences. I think that the other thing that stood out to me is that you use the passive voice/form a lot, when thing are happening, e.g. 'The Orks charged', 'stood their groud', 'opened fire'. If you were to change those to being active - 'The Orks charging', 'standing their groud', 'opening fire' - it becomes more engaging and raises the stakes of the encounter. It shifts the perspective of you narrating the event, to us being there seeing it.
Look forward to seeing what you do next!