Interpret this poem through imagery?

With all the imagery of walls and armies I get the feeling that this poem is based on the fact this young man is not losing his mind but withdrawing into it, the armies perhaps his internal struggle or an issue resolved internally, but he is so far withdrawn his feelings cannot escape and no one can see his revelation, they can only see what appears to be his downfall, him losing his mind- "now you are beyond the reach of our remorse".