Short answers, pulled from the story.
Napoleon crossed the Neman river with 650,000 men in June 1812 and lost at least 370,000 soldiers to fighting, disease, and cold weather conditions. By November only 27,000 fit soldiers managed to cross the Berezina river after the scorched earth policy left them without supplies.
Sweden signed a secret Treaty of Saint Petersburg with Russia on the 5th of April 1812 to oppose France and Denmark-Norway. Charles John declared neutrality and sent diplomats to London and St. Petersburg before forming an alliance basis between Russia, Britain, and Sweden.
The Battle of Leipzig from the 16th to the 19th of October 1813 became known as the Battle of Nations and involved over 250,000 total forces. This engagement occurred after Napoleon won a tactical victory at Dresden but failed to destroy the main Allied army before they escaped encirclement.
The Treaty of Kiel concluded on the 14th of January 1814 ceded Norway to the King of Sweden while Norwegians declared independence on the 17th of May 1814. Bernadotte invaded Norway on the 27th of July 1814 with 40,000 men and established the Union formally on the 4th of November 1814 following the Convention of Moss.
At the Battle of Vitoria on the 21st of June 65,000 French under Joseph Bonaparte were routed by 53,000 British, 27,000 Portuguese and 19,000 Spaniards. Arthur Wellesley pursued and dislodged French troops from San Sebastián which was sacked after a siege before allies reached the Pyrenees in early July.
Napoleon abdicated on the 11th of April 1814 after his marshals mutinied at Fontainebleau on the 4th of April refusing to march further. The Treaty of Paris was signed on the 30th of May 1814 while Allied leaders exiled Napoleon to Elba island and restored Bourbon monarchy under Louis XVIII.