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 , 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.