He tried to regain health by a visit to the hills, but this expedient proved ineffectual, and he was ordered home.

On the 10th of February, 1856, while on his way home on board the Monarch, he died off Ceylon, at the age of sixty-seven, and was buried at sea, just six days after he had been granted the dignity of K.C.B.
Lord Dalhousie's desire to meet his trusted officer was never gratified.

The following correspondence between the Governor-General and Sleeman, now published for the first time, is equally creditable to both parties: BARRACKPORE PARK, January 9th, 1856.
MY DEAR GENERAL SLEEMAN, I have heard to-day of your arrival in Calcutta, and have heard at the same time with sincere concern that you are still suffering in health.

A desire to disturb you as little as possible induces me to have recourse to my pen, in order to convey to you a communication which I had hoped to be able to make in person.
Some time since, when adjusting the details connected with my retirement from the Government of India, I solicited permission to recommend to Her Majesty's gracious consideration the names of some who seemed to me to be worthy of Her Majesty's favour.

My request was moderate.