[4][8][9] He served as mate from around 1840 of the steam paddle-driven Lizard-class gunvessel HMS Locust, which was under the command of Lieutenant-Commander John Lunn, in the Mediterranean.
He was first commissioned to the rank of lieutenant on 30 August 1841, and in September was appointed to HMS Malabar, of 72 guns, Captain Sir George Rose Sartorius commanding, in the Mediterranean.
In July 1851 Mends sailed in her for the Mediterranean (Stopford was later relieved by Henry Francis Greville), until 11 January 1854, when he was promoted Commander.
From 23 January that year Mends was second-in-command to Captain George Elliot on the 91-gun HMS James Watt at Portsmouth, and served on her in the Baltic campaign of the Crimean War (1854–55).
[4] From 22 May 1861 to 10 July 1862 Mends was appointed flag captain of HMS Edgar, a screw-propelled 91-gun second rate launched in 1858, under Rear-Admiral John Elphinstone Erskine, who was second-in-command in the Channel.
Over 80 of these works are in the collection of the National Maritime Museum, more than half of which are from a sketchbook that covers the period of 1850 to 1853, immediately before and during his time on HMS Trafalgar, with some examples in private hands.
[4] Mends died of heart disease, which he had been suffering from for some time, on 15 September 1871, at his home in Seaton Terrace, off Mutley Plain, in Plymouth.