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[Note that the Russian war of 1812 would be considered the 'War of the 6th Coalition' in this scenario.]

After the defeats of the winter in January 1828, and in particular, the heavy losses of the cavalry, the French were sent retreating to recently captured Prussian fortresses and later to the Elbe for want of supplies. In May 1828, the Russian-Prussian offensive against the French on the Oder began and although the French defeated the newly-formed 7th Coalition's offensive, a lack of cohesion, a failure of supplies to reach the frontlines and the cavalry losses will lead to France winning against the Russians and Prussians at Berlin, Bautzen and Frankfurt on the Oder only to be unable to exploit the morale boosting victory produced by the aftermath. In fact, the Prussians and Russians were able to retreat in an orderly order, albeit with heavy losses. More importantly, the Ottoman threat to the Napoleonic Empire from the Balkans to Italy and Central Europe plus the likelihood of Austria and Spain coming onto the side of the 7th Coalition by diplomacy would need to be taken into consideration.

Combat between both sides of the Napoleonic Wars [now under the teenage Napoleon II] would be temporarily halted for the best time to resume after the Oder Campaign, which would occur in Silesia during mid-August 1828. During the period, the Russian and Prussian Armies took advantage of the truce to rearm their armies and secure financial aid from the British and Austrian intervention. Also, the possibility of Austria's defection was likely besides an Ottoman advance from the Balkans to Austria and Italy. Finally, the British might land in Spain or Italy and link up with the advancing Coalition armies from the south.

In this set of events, the Austrian Empire finally came into the seventh coalition. Although there was a last desperate attempt to encircle and rout the Russian and Prussian Armies in a maneuver only to get the Swedish Army encircled at the Battle of Bautzen, it was effectively a dead end as the need for the Grande Army to reorganize in pursuit of the Swedes disrupted defensive operations and pursuit of the Prussians and Russians was made impossible as the French troops on the left flank were already routed when the victorious French III and II Corps came to the rescue.

Following the battle, the Seventh Coalition decided to go on the defensive, but taking into consideration the Trachenberg Plan already developed by the Seventh Coalition. With this in consideration, an offensive by Napoleon against Poznan failed to achieve its objective of knocking the Russians out of the war despite destroying much of the Prussian Army. Two months ago, the Ottomans entered Croatia and the Austrian Army gave battle, but failed. Now, Austria might enter the Seventh Coalition with a deal sealed between Austria and the Seventh Coalition that ceded Austrian Balkan territories in return for the Tyrol and northern Italy. Austria could regain the Balkan territories after the Napoleonic Wars, though.

The final destruction of the Spanish Navy on 10 February 1828 and the defeat and destruction by burning of the French Atlantic Fleet's Brest Squadron by the Royal Navy the same day, which cost Napoleon II 20 ships of the line and 10 frigates off Cadiz would lead to Spain's defection from the Napoleonic side of the Seventh Coalition. Without Spain's assistance, the Napoleonic offensive against Russia in Silesia saw several corps intended for the offensive diverted to the Pyrenees, and the replacements were taken from Italy. After repeated British attacks, Joachim Murat's Naples was forced to surrender to the Royal Navy's reinforced Mediterranean Fleet after amphibious landings on 29 August 1828. The Royal Navy then invaded the Napoleonic Italian Kingdom to threaten the flanks and force an Austrian declaration of war on Napoleon, which occurred on 30 November, besides diverting Napoleonic troops to deal with the Austrian and British threat to the south.

The Russians had retreated to Poland, but the Napoleonic Grande Armee's elite troops and cavalry were in Bavaria waiting for the imminent French offensive. On 20 April 1829, reinforced by the British and Ottoman Armies and deceptions about an offensive against the French Mediterranean coast, the Seventh Coalition attacked across a front stretching from Stettin to Salzburg and from Perpignan to Genoa. After the recapture of Berlin on 15 May and a general defection of German troops to the coalition, the French Pyrenees Army was stripped of vital reinforcements and the Spanish Army was able to enter Perpignan on 10 July. Then, the Spanish Army advanced onto Toulon, only to be temporarily repulsed on the Rhone from 19 August to 20 September 1829 and by mid October, France was severed from its Mediterranean coast thanks to the assistance of Ottoman, American, Neapolitan, Italian and British troops. All these were helped by the elimination of the French Atlantic Fleet on 11 April 1829 that resulted in the depletion of the Grande Armee in Germany as reinforcements had to be sent to coastal defence duties.

It must be noted that Napoleon II never had a significant interest in developing the steamship, which was first used by the Royal Navy starting 1819. By 1825, there were two dozens steamers in the Royal Navy, albeit all of them being paddle wheeled. Why Napoleon II and Admiral Cosmao Kerjulien lacked the initiative to build sufficient steamships [only 5 ships of this type were used in combat, with the rest being scuttled by the end of the war] was never justifiable, but Napoleonic obsession with huge quantities of sailing ships of the line and frigates being built to win the naval war against Britain and the growing Seventh Coalition was the most likely reason. Another reason was distrust over the usage of the new technology and the likeliness of winning the naval war of sail in quantities and attrition with British steamship construction, which never significantly diverted resources from the superiority of the Royal Navy in sail, the British Army and supply production and even funds for the Seventh Coalition.

Although the American contribution was minimal, consisting of only a corps of troops in Europe, nevertheless, it is worthy of interest to discuss this point. The American corps, consisting of 3 divisions with 10,000 men each, was first involved in the Peninsular campaign until its evacuation from Spain. Then, it was stationed in Britain and involved in diversionary operations off Cadiz that led to the destruction of the French Atlantic Fleet that sortied from Brest in December 1827. The same fleet was to rendezvous with the Spanish Fleet and sortie into the Mediterranean to destroy the British Mediterranean Fleet, knock the Ottomans from the war and return to Brest, but it was caught off Cadiz on 21 January 1828, with its presence being reported to the Royal Navy's Channel Fleet, which sortied to meet the British Cadiz squadron and defeat the combined fleet once and for all, reminiscent of Trafalgar. All Spanish ships involved [and all the operational Spanish frigates and ships of the line] were destroyed or captured as the French made their escape from the battle and later Cadiz a week after, leaving any Spanish and disabled ships to capture by Britain and Spain.