Promoted to rear-admiral on 27 August 1851, Wallis became Commander-in-Chief, South East Coast of America Station, with his flag in the third-rate HMS Cumberland, in May 1857 but only held the command until September 1857.
He was promoted to vice-admiral on 10 September 1857, appointed a Knight Commander of the Order of the Bath on 18 May 1860 and promoted to admiral on 2 March 1863.
He was appointed Rear-Admiral of the United Kingdom on 17 July 1869 and Vice-Admiral of the United Kingdom on 12 February 1870.

In order to prevent admirals from dying as paupers, a special clause in the retirement scheme of 1870 provided that those officers who had commanded a ship before the end of the Napoleonic Wars should be retained on the active list: the six days Wallis was in command of HMS Shannon qualified him to remain on the active list until he died.
He was advanced to Knight Grand Cross of the Order of the Bath on 24 May 1873 and promoted to Admiral of the Fleet on 11 December 1875.
The Admiralty suggested he retire when he reached his late nineties, as being on the active list meant he was liable for calling up for a seagoing command.
Wallis instead replied he was ready to accept one.

Wallis died at his country home in Funtington in West Sussex on 13 February 1892 and was buried in St Mary's churchyard at Funtington.
He was only a few months short of his 101st birthday with a combined service of 96 years from the time his name first appeared on the books of a Royal Navy ship.
He was the last survivor of the action between HMS Shannon and USS Chesapeake, and on his death, four admirals below him on the active list were able to gain immediate promotion.
Promoted to rear-admiral on 27 August 1851, Wallis became Commander-in-Chief, South East Coast of America Station, with his flag in the third-rate HMS Cumberland, in May 1857 but only held the command until September 1857. He was promoted to vice-admiral on 10 September 1857, appointed a Knight Commander of the Order of the Bath on 18 May 1860 and promoted to admiral on 2 March 1863. He was appointed Rear-Admiral of the United Kingdom on 17 July 1869 and Vice-Admiral of the United Kingdom on 12 February 1870.
In order to prevent admirals from dying as paupers, a special clause in the retirement scheme of 1870 provided that those officers who had commanded a ship before the end of the Napoleonic Wars should be retained on the active list: the six days Wallis was in command of HMS Shannon qualified him to remain on the active list until he died. He was advanced to Knight Grand Cross of the Order of the Bath on 24 May 1873 and promoted to Admiral of the Fleet on 11 December 1875. The Admiralty suggested he retire when he reached his late nineties, as being on the active list meant he was liable for calling up for a seagoing command. Wallis instead replied he was ready to accept one.
Wallis died at his country home in Funtington in West Sussex on 13 February 1892 and was buried in St Mary's churchyard at Funtington. He was only a few months short of his 101st birthday with a combined service of 96 years from the time his name first appeared on the books of a Royal Navy ship. He was the last survivor of the action between HMS Shannon and USS Chesapeake, and on his death, four admirals below him on the active list were able to gain immediate promotion.
Provo Wallis