alternatehistory.com

In the aftermath of the Russian surrender of 1813, the most the British Army could do in Europe was to land in Norway in 1812 and Zealand in 1813 and destroy most of the Danish-Norwegian Navy with Swedish support [the third major victory for the Royal Navy during the Napoleonic Wars after the capture of the Portuguese Navy in 1807 and the destruction of the combined French-Spanish Navy off Trafalgar in 1809, having barely avoided the same defeat in October 1805 by Villeneuve's carriage departure to Paris], but the Royal Navy, having been reinforced with American support since the impressment of its sailors ended and having allowed the United States to invade Florida, Cuba and Mexico with concessions in their favour, was sweeping the French Navy from the world's oceans, reducing its threats of piracy and interference in the world's oceans. Now, the only war going on between Britain and France against Napoleon after 1813 was the war at sea, with the British capturing several French frigates, most of the Danish-Norwegian Navy and a ship of the line [Haultpolt, by 24 pounder gunned-American frigates and shore defences during a raid on Washington D.C. on 17 August 1814].

In America, the navy was building new ships at a rapid pace for its national size. By 1820, the American Navy had 8 ships of the line, 20 frigates and a variety of smaller vessels. Besides Haultpolt, the Americans captured the French frigate Renomee [o.t.l. HMS Java from 1811] on the day after the failed Washington D.C. raid and Nereide on 29 December 1812, with the latter frigate being scuttled from damage received. Also, the fledging American state was expanding into ex-French and Native American territory.

In the aftermath of the 1815 Tambora Eruption and the 'Year without a Summer' that followed, the British decided to provide Napoleonic France with a truce lasting 5 years and starting to be effective from 15 January 1817, after protests and starvation in Britain. This would last 5 years and America would be responsible for supplying and transferring the needed food supplies to Continental Europe, along with the French Atlantic Fleet and Spanish Navy covering their ships and filled with the stated food supplies. A truce in which the French and British stopped active combat was achieved during the Napoleonic Wars, but it was as effective as Amiens without the treaty. Also, a mass exchange of prisoners of war was to be completed by 1817, having been started in the same year.

The prisoner exchange began on 1 February and involved plenty of British naval ships, mostly prizes taken from 1793-1816. An explanation as to the majority of ships used as such was because there was the possibility that some of the former French ships might be returned to French naval service, even though there was no indication of this. By the end of 1817, 30000 French and Spanish troops [mostly colonists, servicemen, auxillaries and sailors] were returned to their homelands, with all willing British troops being released from captivity to return to Britain and empire. Also, plenty of imported supplies from outside Europe were imported to Napoleon's Empire and its allies, enough to last them for 8 if not 10 years.

After Napoleon's death on 5 May 1821, however, things began to change. The French Navy was readied to defeat the United Kingdom. This time, it would be with all fireships and bomb vessels available to the French, Spanish and Danish navies and it would be launched on the 156th anniversary of the Great Fire of London, with the French targeting the Royal Navy's Channel Fleet for destruction. The combined fleets set off to defeat the British.

Having set sail on 31 August 1822, 3 of the 5 French and Spanish fire ships to reach Portsmouth were able to enter Portsmouth Harbour and set 15 Royal Navy ships of the line and frigates combined on fire before it was put out. To make things worse, the British capital at London was burnt by several French, Batavian and Danish ships, combined with local British republicans, revolutionaries and Napoleonic supporters. The Napoleonic Wars would resume from this moment.