Abraham Lincoln was, and still is, an iconic figure in America. In the poem, the "captain" mentioned is actually a metaphor for the great figure of Abe Lincoln. Not only is he represented as a person that the country admired, but more specifically, as a person that he admires. This further enhances the purpose of the poem because it adds in the perspective of the poet. Another extended metaphor throughout his poem would be the "fearful trip" that Whitman refers to in his first line. This trip represents the Civil War. Whitman's style of writing seems to be to allude to certain historical events, people, and places. Another example of this would be the metaphor of the "ship", which represents America in the Civil War. All of these metaphors add to the essence of the poem in that it embellishes Whitman's style, while also proving the importance and commemorating the life of Abe Lincoln.
Whitman's word choice also greatly contributed to the style and purpose of his piece. He uses the word "father" as a substitute for "captain", ultimately displaying his deep respect that he has for Lincoln, otherwise known as the father of the union. In contrast, Whitman also uses the words "grim" and "daring" along with phrases such as "cold and dead" to overcast the celebration of Lincoln, and memorialize the sorrow of his death. These words are a great appeal to pathos, as well as gives the poem multiple tones in order to both encapsulate his audience while also keeping Lincoln's death in mind.
Whitman's poem is a great example of an effective poem, because not only is it short and sweet, but it also shows Whitman's respect and need to honor one man. In order to memorialize and honor Lincoln, Whitman uses specific word choice and extended metaphors. In this regard, he successfully gets his message across to his audience, and honors one of our greatest presidents.