What is the author's style in The Arsenal at Springfield by Henry Wadsworth Longfellow?

The most obvious technique that Longfellow uses is metaphor. The organ of war comes to life from the moment he describes the guns as a musical instrument. This thought is compelling, especially since it is a contradictory metaphor. The idea of using a peaceful instrument to describe items that are used to create violence immediately engages the reader's attention. However, Longfellow takes it several steps further by sustaining the metaphor. The "huge organ" with its "burnished arms" takes on an even more sinister connotation when the "death-angel touches those swift keys!" Once this horrendous piece of death machinery is activated, the war organ seems to explode into the "awful symphonies," which drown out the "loud lament" of people who are suffering.