Answer:
The meter and rhyme create the mood of anxiety and apprehension
Step-by-step explanation:
Rhyme and meter beautify the poem. Longfellow has used iambic pentameter and varied rhyme scheme in this 15-line fifth stanza. The rhyme is abba cc dd ee ff gg with line 11 stand alone. 'Dead' and 'spell' shows the anxious mood since 'secret dead' reveals stressful apprehension. 'Hill' and 'still' show the place and horrible silence where people were caught and killed. Dread and tread is coming of more such horrible scenes of dead people. Though the air tells 'all's well', there is an apprehension of 'the place and the hour'. The line not rhymed exhibits the tense mood since the 'thoughts are bent' which means the mind is not in proper thinking mood because of deadly environment. In the river, 'a line of black' is the horror that is in the offing.