Below, you'll see any text that was highlighted with comments from the reviewer.
I like this, it's something I'd rather see in my English textbooks than what we have now.
I think speech is a main factor, you're doing well, really, but some things here and there can be shortened or combined to make the piece more sturdy (highlighted).
Cruelty is defining for the invaders, I don't need to know what makes them cruel, as a reader, my interest pulls me to want to know how they are monsters. If your character is cruel, be cruel to them.
This is constructive criticism, don't take it harshly. Open your mind to these opinions and take into consideration the prompt. If you find that you didn't like this review, don't let it get you down. The story is good, but it's still in the early stages, you're doing great!
I didn't really go past the archer's point, it's easy to apply what I said to the rest of the story.