Shelley stopped working on the poem following the death of his daughter Clara Everina Shelley on 24 September 1818. After her death, Shelley began to travel across Italy, and would not progress with the drama until after 24 January 1819. By April, the majority of the play was completed, and Shelley wrote to Peacock on 6 April 1819: "My Prometheus Unbound is just finished, and in a month or two I shall send it". Shelley also wrote to Leigh Hunt to tell him that the play was finished. However, the play was not yet published; Shelley would be delayed in editing and finishing the work by another death, that of his son William Shelley, who died on 7 June 1819.