Here's the actual poem "This Dust Was Once the Man" by Walt Whitman so we can visualize the end of each line:
<em>This dust was once the </em><em>man</em><em>,</em>
<em>Gentle, plain, just and resolute, under whose cautious </em><em>hand</em><em>,</em>
<em>Against the foulest crime in history known in any land or </em><em>age</em><em>,</em>
<em>Was saved the Union of these </em><em>States.</em>
The literary device that this poem include at the end of each line is <u>assonance</u>, as assonance refers to the repetition of similar or identical vowel sounds in two or more words, even when they start with different consonant sounds. The end of number line 1 and 2 has the words "man", and "hand" which has the same vowel sound of "an"; and the last word of line 3 and 4 have the same vowel sound as well: "age" and "States".