 While Governor-in-Chief at Sierra Leone, from 16 May 1892 to January 1894, he witnessed in November 1892 the first systematic strike of the 800 underpaid labouring men of the Royal Engineers' Department in the history of that colony.Fleming was knighted on 1 January 1892, and in the same year he married Constance Mary Kavanagh (1858–1950), daughter of Maurice Dennis Kavanagh (1821–1899) and Mary Constantia "née" Clifford (1825–1898) and granddaughter of Hugh Clifford, 7th Baron Clifford of Chudleigh.Their only son, Hugh Joseph (born 26 Jan 1895 in Warwick), became a Sec.-Lieut., and was killed in action during WWI on 24 August 1916 at Nord-Pas-de-Calais, France.