In this scene the author uses a simile to drive his poem. The line "Across the moon like a prison bar," is a simile because the ship is being compared to a prison bar using the word like.
"And startled the pigeons from their perch," is the quote that was said when Paul Revere's friend climbed to the top of the tower. The poetry used hear was imagery and helps the reader envelope themselves in the poem.
"Masses and moving shapes of shade" is an example of alliteration and assonance. It helps the story flow and stick detail into the readers mind. The alliteration was Masses and moving and the assonance was shapes and shade
"The watchful night-wind, as it went Creeping along from tent to tent, And seeming to whisper, 'All is well'." The literary term used was personification and it helps set a mood. The personified thing was the wind talking.
"As it rose above the graves on the hill", this being an example of imagery reffering to your sight and the personification of the tower rising helps bring the reader into the story like they were there.
"The fate of a nation was riding that night" The literary term here was assonance as in fate and nation. It helps make the message more impactful to the reader.