In "O Captain! My Captain!" Walt Whitman portrays Lincoln as the captain of a ship (the "ship of state" being a frequently-used metaphor) and the people of the United States as the crew of the ship. Through this metaphor, he emphasizes the significance of Lincoln's assassination. The "captain," having steered the "ship" through a "fearful trip," is now dead. The loss belongs to every one of the "crew," or the people of the United States.

In the second stanza, he even abandons the metaphor to describe the "bouquets and ribbon'd wreaths" that are displayed in his honor, and "the swaying mass" of people that look to him for adulation. In the final stanza Whitman writes that the "ship is anchor'd safe and sound" but without its captain. The people are deprived of the ability to shower adulation on the great man who has steered them through the worst storm in the history of the nation—the Civil War.

The people will cheer the end of the war, but Whitman (and it seems the people as a whole) cannot feel the exultation of victory because his captain, President Lincoln, is gone. The poem, published in the November following Lincoln's death in April, captured for many readers the sense of grief and of joy that accompanied the end of the war.