Some of Pitt's domestic plans were not successful; he failed to secure parliamentary reform, emancipation, or the abolition of the slave trade although this last took place with the Slave Trade Act 1807, the year after his death. Biographer William Hague considers the unfinished abolition of the slave trade to be Pitt's greatest failure. He notes that by the end of Pitt's career, conditions were in place that would have allowed a skillful attempt to pass an abolition bill to succeed, partly because of the long campaigning Pitt had encouraged with his friend William Wilberforce. Hague goes on to note that the failure was likely due to Pitt being a "spent force" by the time favourable conditions had arisen. In Hague's opinion, Pitt's long premiership, "tested the natural limits of how long it is possible to be at the top. From 1783 to 1792, he faced each fresh challenge with brilliance; from 1793 he showed determination but sometimes faltered; and from 1804 he was worn down by ... the combination of a narrow majority and war".