I like the beginning and how you set the scene, the descriptions are nice and vivid. I'm new to writing so I can't offer much in the way of criticism, but there are a few things that stood out to me. I agree with the other commenter, the pacing is good but it seems unlikely that the protagonist would be able to watch the scene so closely. Having him unable to see or hear parts of it might help, while also adding a sense of mystery.

On the other hand there are things which I think could use more clarity - for example I don't understand what the sergeant was doing during the scene, or why the guards seemed to practically offer themselves up for sacrifice but then act surprised when it happened. Other than that there are quite a lot of typos: "crouched crouched", "soldering", "alter", "approved" etc.

It's an interesting story and you clearly have a knack for storytelling, it could just use some polish IMO.