What image does the poet convey of the soldier in the poem?

Please help me for my incoming English Exam. We're reading this poem called " The Soldier " by Rupert Brooke. It's mainly about his time before he went to war. It describes patriotism, self-sacrifice, devotion etc. Although, I don't know how to formulate those ideas in a paragraph. If possible, please give me specific points about one of the themes above or ( all if possible ) so that I can use your wonderful and helpful ideas for my exam!

Thank You For Your Greatful Help!