He entered the navy during the Spanish armament in 1790 and served aboard a number of ships, starting at the level of able seaman and rising through the ranks, having reached midshipman on the outbreak of the French Revolutionary Wars.

He was afterwards employed in the English Channel and North Sea, where he distinguished himself on a cutting out expedition off the Dutch island of Schiermonnikoog, narrowly escaping death when a ship he tried and failed to board suddenly exploded.

[1][2] He entered the navy on 1 July 1790, during the Spanish Armament, serving as a volunteer aboard the 64-gun HMS Ardent, which was then under the command of Captain James Vashon.

His next ship was the 50-gun HMS Severn, under Captain Paul Minchin, where he was rated as midshipman some time before the outbreak of war with Revolutionary France in February 1793.

[1][2] Humphreys was next in action supporting the army under Sir Ralph Abercromby at the siege of Saint Lucia, and afterwards convoyed the despatches concerning the attack on Porto Rico back to Britain.

[2] His promotion to lieutenant came on 17 January 1797, together with an appointment to the armed ship Sally, serving in the North Sea under Captain George Wolfe.

[1] In August 1798 Humphreys was sent with some of Juno's men to support a cutting out expedition led by Captain Adam Mackenzie of HMS Pylades off the island of Schiermonnikoog.

[5] The strong tide meant that he could not maintain his station alongside the Dutch vessel, and the roundness of her sides prevented him from leaping aboard.

[4] After the Anglo-Russian invasion of Holland in August 1799 Humphreys left Juno and moved to the 50-gun HMS Isis, which was then the flagship of Vice-Admiral Sir Andrew Mitchell with the Channel Fleet.

[1][7] Despite his promotion, Humphreys had to wait nearly two years before receiving his own command, until finally appointed to the bomb vessel HMS Prospero at Portsmouth in January 1804.

Sent to enforce Berkeley's order, Captain Humphreys located Chesapeake off Norfolk, Virginia on 22 June and sent a lieutenant across to request permission to search her.

[1] Anxious to appease the Americans, an Order in Council was issued, banning the use of force against foreign warships, Berkeley was recalled and Humphreys too found himself a victim of political movements.

[12] Humphreys spent the remainder of the war ashore on half-pay, finding occupation in civil duties, serving as a Justice of the Peace for Buckingham, Chester and Lancaster.

[14][15] After the wars had ended he was put on the list of superannuated captains, but achieved some recompense when he was made a Companion of the Bath on 26 September 1831, on the occasion of King William IV's Coronation Honours.

[14][17] He settled at Bramall and had become widely respected in the Stockport area prior to his wife's inheritance, but following his succession to the estate there were disputes from other members of the Davenport family who claimed a right to the property.