On the outbreak of Napoleonic Wars Austen was appointed to raise and organise a corps of Sea Fencibles at Ramsgate to defend a strip of the Kentish coast.

[4] Austen became Flag Captain to Lord Gambier, in the second-rate HMS Neptune in August 1801 and earned a reputation for seeing to the welfare and health of his men.

[4] On the outbreak of Napoleonic Wars he was appointed to raise and organise a corps of Sea Fencibles at Ramsgate to defend a strip of the Kentish coast.

[4] He went on to be commanding officer of the fourth-rate HMS Leopard, flagship of Rear Admiral Sir Thomas Louis, in May 1804 and then took part in the blockade of Boulogne.

[4] He next became commanding officer of the third-rate HMS Canopus, a French ship of the line captured in the Battle of the Nile (as the Franklin), early in 1805.

[4] In HMS Canopus he took part in the pursuit of the French Fleet, under the command of Admiral Pierre-Charles Villeneuve, to the West Indies and back in Summer 1805.

[4] On 13 July 1808, the East India Company gave Austen £420 with which to buy a piece of plate: this was a substantial gift (perhaps the equivalent of a year's salary) in thanks for his having safely convoyed to Britain from Saint Helena seven of their Indiamen, plus one extra (voyage chartered) ship.

[4] Austen became Flag Captain to Lord Gambier, Commander-in-Chief of the Channel Squadron, in the first-rate HMS Caledonia in September 1810.

[6] His main role was to protect British commercial interests during the Mexican–American War, which broke out in 1846, and to disrupt the activities of slave traders.