He saw action in command of a ship of the line at the Battle of Cape Finisterre in 1805, before supporting operations off the Río de la Plata in 1806 and 1807.

[1][2] He entered the navy in January 1782, serving as a midshipman aboard the 64-gun HMS Sampson under the command of Captain John Harvey, who was a relation of Warren's.

[2][4] He took her out to the West Indies and enjoyed considerable success against French warships, privateers and merchant vessels over the three-year period of his command.

[5] Before his departure from the Caribbean, Warren received the thanks of the House of Assembly of Tobago for his services, and sailed back to Britain to pay off Scourge.

[2][4] Warren left Glory in July the following year, still serving with Stirling and going out with him as a passenger aboard HMS Sampson to participate in operations off the Río de la Plata.

[2][3] On their arrival off Montevideo Stirling appointed Warren to command his flagship, the 64-gun HMS Diadem, and the navy operated in support of the assault on the city.

Warren was ordered to join the fleet in the North Sea, blockading the Dutch ports as part of Rear-Admiral Alan Gardner's squadron.

[10] The British commander promptly ordered the luggers to be burnt, reboarded his men and landed them next to the nearest Russian shore battery.

The battery, defended by 100 sailors, was stormed and carried, the British spiked the guns and destroyed the magazine, before returning to the ships with only five men wounded.

[8] Hawkey was killed in the attempt, but Bellerophon's Lieutenant Charles Allen took over command, and six of the gunboats were captured, and a seventh destroyed, with 12 craft containing stores for the Russian Army also being taken.

[2][4][13] He was assigned to transport Lucien Bonaparte, Napoleon's brother, and his family from Malta to England, after which he sent to reinforce the British squadrons in the East Indies.

[4][14] After the surrender of the island to the British on 18 September by General Jan Willem Janssens, Warren accompanied the commander in chief, Vice-Admiral Robert Stopford, back to Britain.

[4] Warren became resident agent of transports at Deptford in January 1830, and commodore in the Thames in 1831, commanding the yacht HMY William and Mary.