[1] He was the fourth of his line since his great grandfather, Sir Charles Knowles, admiral, was created a baronet for purely naval services in 1765.

With a fleet larger than any two rivals combined, there were to be no major battles fought, just localised military action buttressed by the Royal Navy.

[citation needed] On 29 November 1872 he was appointed captain and given command of HMS Lapwing, a plover class wooden screw gunvessal.

[1][2] Knowles joined at Sheerness as Senior Naval Officer of the Barbados Division in the West Indies in command of HMS Blanche, a 1760-ton, 6 gun Eclipse class wooden screw sloop (launched in 1867 and sold off for breaking in 1886), from 4th Sept 1877 - 26 November 1881; He was thanked by the admiralty for services in quelling the uprising in the Danish Island of Santa Cruz in 1880;[1] then appointed Captain in command of HMS Shannon, the first British armoured cruiser and last Royal Navy ironclad to be built with a retractable propeller to reduce drag when under sail (launched 1875 and scrapped 1899), ship of first reserve, coastguard, Greenock on the north coast of Ireland from 4 August 1885; He finally retired from active service on 14 March 1887, having spent a total of fourteen years and two hundred and twenty days at sea; Rear-Admiral 1 January 1889; Vice-Admiral 18 January 1894.

He married secondly Mary Ellen Thomson on 11 June 1882, the grand daughter of the Hon Joseph Howe, Lt Gov of Nova Scotia.