What is the title of the poem by Walt Whitman that reflects on the assassination of President Lincoln?

The poem that reflects on the assassination of President Lincoln is "O Captain! My Captain!" This piece is a poignant tribute to Lincoln, where Whitman uses the metaphor of a captain of a ship to symbolize Lincoln’s leadership during the tumultuous times of the Civil War and his subsequent assassination. The poem’s structure, with its rhythmic lines and heartfelt imagery, conveys deep sorrow and loss, capturing the national mourning following Lincoln's death.

While other poems by Whitman, such as "Song of Myself" and "When Lilacs Last in the Dooryard Bloom'd," explore themes of life, death, and the human experience, they do not specifically focus on Lincoln's assassination in the same immediate and personal way as "O Captain! My Captain!" does. "Out of the Cradle Endlessly Rocking" deals with different themes of nature and loss, again not directly addressing the events surrounding Lincoln's assassination. Thus, "O Captain! My Captain!" stands out as a dedicated elegy for the president.