Wooden walls in Portsmouth Harbour.

This old postcard shows HMS Victory, Nelson's flagship at the Battle of Trafalgar, afloat in Portsmouth Harbour. There's no clue to the date but she remained afloat until 1922, when she was moved into dry dock in the harbour where she remains to this day, 246 years after she was launched at Chatham Dockyard.

Portsmouth harbour was graced by several 'wooden walls' during the latter half of the 19th. century, serving as training and accommodation ships when the pace of technological change rendered them redundant as active warships.

This is the training ship HMS St. Vincent, looking very smart apart from a forest of incongrous, makeshift davits protruding from her hull. She was laid down in Portsmouth harbour as a 120-gun first rate ship of the line in 1806, the year after the Battle of Trafalgar and 5000 spectators came to watch her launching in 1815, the year of the Battle of Waterloo. She was one of three sister ships named after great admirals, the others being HMS Nelson and HMS Howe and was the last of the three to survive, serving as flagship at Portsmouth and in the Channel and Mediterranean in the 1840s. From the 1870s onwards she served as a boys' training ship at Portsmouth and was broken up in 1906.

... and here's HMS Duke of Wellington, once the 131 gun flagship in the Baltic of Sir Charles Napier and typifying the transition from sail to steam power - she used both. She was launched as HMS Windsor Castle on 14th. September 1852 but on that very same day the Duke of Wellington died, so she was immediately renamed after the national hero of Waterloo. Some time after this picture was taken, in her last year of active service as flagship to the Commander-in-Chief at Portsmouth, her masts were removed and she was relegated to role of depot ship for berthing the Portsmouth Dockyard Reserve before being broken up in 1904. Here she's pictured dressed overall, firing a salute on Queen Victoria's birthday in 1896.

The two pictures above come from the 1896 edition of The Navy and Army Illustrated.