This officer obtained his first commission about the year 1793; and in 1798 we find him serving as senior Lieutenant of the SHEERNESS 44, bearing the broad pennant of Commodore James Cornwallis on the African station.
There is a privilege existing from time immemorial which is not enjoyed on any other station than that of the coast of Africa; it is that of the next officer giving himself the rank of his deceased superior; and which self-appointment have ever been held good by the Admiralty. Commodore Cornwallis died of a fever July 31, 1798; when Lieutenant Hanwell who succeeded him in the command of the Sheerness, gained two graduations of rank, which on his arrival in England was confirmed by a post commission, dated December 29 1798.
More on Admiral Hanwell.
Early in 1810, Captain Hanwell obtained the command of the GRAMPUS, A 50 gun ship. On the 26th October, in the following year, he was tried, by a court- martial, upon a charge of repeated drunkenness and unofficer-like conduct, preferred against him by Lieut. John Cheshire; but the Court agreeing that the charge was not proved, acquitted him; observing that the prosecution seemed to be malicious and vexatious. He subsequently commanded the DICTATOR 64; and during the latter part of the war superintended the depot for prisoners of war at Norman Cross.
From the Maritime information Centre..
Admiral Hanwell married in 1800, Miss Hanwell of Mixbury, near Brackley, in Northamptonshire".