What emotion is primarily expressed in "O Captain! My Captain!"?

"O Captain! My Captain!" is a poignant poem by Walt Whitman written in response to the assassination of President Abraham Lincoln. The primary emotion expressed in the poem is sorrow, as the speaker mourns the loss of their leader and reflects on the impact of Lincoln's death on the nation.

Throughout the poem, there is a tone of deep grief and melancholy, as evidenced by phrases that convey a sense of tragedy amidst the celebration of victory in the Civil War. The juxtaposition of the joyful return from battle with the sorrowful reality of the captain's death amplifies this emotion. The recurring exclamation "O Captain! My Captain!" serves to personalize the loss, illustrating both admiration and profound sadness for Lincoln’s untimely demise. The poem encapsulates a national mourning that resonates with themes of loss and the complexities of grief following a monumental victory, thereby underscoring the sorrow that permeates Whitman's reflections on leadership and sacrifice.