In 1667, as Commander-in-Chief in the West Indies, he sailed into Martinique, silenced the forts and destroyed 20 of the 24 French ships there, including the flagship. He also captured Surinam from the Dutch. In the Third Dutch War he fought as a flag officer in Sandwich's squadron at Solebay in 1672 and Prince Rupert's at the Texel in 1673, shortly before his death. The portrait is inscribed 'Capt. Harman'.

It is perhaps the most dashing of the 'flagmen of Lowestoft' series commissioned by James, Duke of York, and was one of those seen by Pepys, either begun or finished, in Lely's studio on 18 April 1666. Lely, a Dutchman who arrived in England in 1641 after the death of van Dyck, soon became his successor as leading portraitist of the day. He worked for Charles I, continued to flourish under the Commonwealth and Protectorate, and after the Restoration of 1660 was appointed Principal Painter to Charles II. The full 'flagmen' set consists of 13 individual portraits, of which George IV presented 11 plus a copy of that of Admiral Sir John Lawson (BHC2833) to Greenwich Hospital in 1824. The originals of Lawson and of Prince Rupert were retained in the Royal Collection, although William IV presented an extended full-length copy of the latter (BHC2990) to the Hospital in 1835.