Six times! That's how many times the word England or English occurs in this poem. (Just go ahead and count 'em. We'll wait right here.) So, you think "The Soldier" is patriotic? You could say so. The speaker emphasizes the organic relationship between the soldier and his country—the soldier is a part of England, and England is like his mother. In doing so, he underscores the importance of fighting for that country.
A country is like a mother. In fact, it plays a bigger role in our development as human beings than our own parents. Love it, or leave it!
Self-interest alert! Patriotism is merely the speaker's way of convincing himself that his death will not be in vain, and that he'll be rewarded in heaven.