"The Somerset, British man-of-war; A phantom ship, with each mast and spar Across the moon like a prison bar." This is a simile because it uses like. The meaning of the usage of the simile is describing the ships masts and spars like prison bars across the moon.
"A shape in the moonlight, a bulk in the dark, And beneath from the pebbles, in passing, a spark Struck out by a steed that flies fearless and fleet: That was all! And yet, through the gloom and the light, The fate of a nation was riding that night." This metaphor is showing how paul revere is like a spark that is lighting a revolution.
"The watchful night wind as it went." This is personification because it is describing the wind as watchful which is a particular human trait.
"Wrapped in silence so deep and still That he could hear, like a sentinel’s tread." The tone of the poem is hushed you can tell this because of how the words are like silenced.
"Midnight message." This is alliteration because of midnight and message start with the same sound.
"measured tread" This is assonance because of the repeating vowel sounds through it.