By 1867, Whitman's major work as a poet was done. After the death of Abraham Lincoln, he completed his book of war poems, Drum Taps. Whitman's remaining years would be spent re-editing Leaves of Grass, writing prose, and cultivating his reputation throughout the world. He began giving an annual lecture on Lincoln's death, a lecture that drew on the eyewitness testimony of his companion Peter Doyle, who was in Ford's Theatre when Lincoln was assassinated.