In 1848 the Residency at Lucknow again fell vacant, and Lord Dalhousie, by a letter dated 16th September, offered Sleeman the appointment in the following terms: The high reputation you have earned, your experience of civil administration, your knowledge of the people, and the qualifications you possess as a public man, have led me to submit your name to the Council of India as an officer to whom I could commit this important charge with entire confidence that its duties would be well performed.

I do myself, therefore, the honour of proposing to you to accept the office of Resident at Lucknow, with especial reference to the great changes which, in all probability, will take place.
Retaining your superintendency of Thuggee affairs, it will be manifestly necessary that you should be relieved from the duty of the trials of Thugs usually condemned at Lucknow.
In the hope that you will not withhold from the Government your services in the capacity I have named, and in the further hope of finding an opportunity of personally making your acquaintance, I have the honour to be, Dear Colonel Sleeman, Very faithfully yours, DALHOUSIE.[4] The remainder of Sleeman's official life, from January, 1849, was spent in Oudh, and was chiefly devoted to ceaseless and hopeless endeavours to reform the King's administration and relieve the sufferings of his grievously oppressed subjects.

On the 1st of December, 1849, the Resident began his memorable three months' tour through Oudh, so vividly described in the special work devoted to the purpose.

The awful revelations of the _Journey through the Kingdom of Oude_ largely influenced the Court of Directors and the Imperial Government in forming their decision to annex the kingdom, although that decision was directly opposed to the advice of Sleeman, who consistently advocated reform of the administration, while deprecating annexation.

His views are stated with absolute precision in a letter written in 1854 or 1855, and published in _The Times_ in November, 1857: We have no right to annex or confiscate Oude; but we have a right, under the treaty of 1837, to take the management of it, but not to appropriate its revenues to ourselves.