Can someone EXPLAIN this poem please?

Question

Sonnet

On Seeing A Piece of Our Heavy Artillery

Brought into Action

Be slowly lifted up, thou long black arm,

Great Gun towering towards Heaven, about to curse;

Sway steep against them, and for years rehearse

Huge imprecations like a blasting charm!

Reach at that Arrogance which needs thy harm,

And beat it down before its sins grow worse.

Spend our resentment, cannon,-yea, disburse

Our gold in shapes of flame, our breaths in storm.

Yet, for men's sakes whom thy vast malison

Must wither innocent of enmity,

Be not withdrawn, dark arm, the spoilure done,

Safe to the bosom of our prosperity.

But when thy spell be cast complete and whole,

May God curse thee, and cut thee from our soul!

Answer 1

It sounds pretty self explanatory to me. You might be trying to read more into it than needs be. Aren't cannons, almost always, the first displayed in battle conflict. Sounds more like an Iron Maiden tune.

Answer 2

Ask the poet, not us.  How the h**l should we know?