Timeline of the 19th century. France is a dominant power early on, but the main power later is the British Empire. Spain is also powerful due to British support in the Americas.
1801: Beginning of Barbary War.
1803: Louisiana Purchase.
c.1803: The Napoleonic Wars begin.
1804: Austrian Empire founded.
1805: End of the Barbary War.
1806: Holy Roman Empire dissolves.
1807: British Empire declares slave trade illegal.
1810: Beginning of the Rebellion of New Spain. (OTL Mexican War of Independance, but Spanish victory)
1812: French invasion of Russia is the turning point for the Napoleonic Wars.
1812: Beginning of War of 1812.
1814: Treaty of Ghent.
1815: Battle of New Orleans, British victory after the war was officially over.
1817: Meeting of the Armies, War of 1812 ends with annexation of the United States of America. The fall of this country has effects across the world. Some colonies see that it is impossible to separate from their master countries, while others want to show that they can do better than the US did.
1819: Wellesley-Onís Treaty, Florida is ceded to the British Empire and colonial border in North America is finalised. Britain promises to aid Spain in the Rebellion of New Spain in exchange for money to pay off Britain's foreign debt.
1821: End of the Rebellion of New Spain; with British help, the Spanish defeat the rebellious colony.
1821 - 1827: Britain continues to aid Spain; no Spanish North American colonies gain independance except those which already have, but these are reconquered. See Rebellions of Spanish America.
1822: Brazil becomes independant with Portuguese royalty as the emperor of the Empire of Brazil.
1823: No Monroe Doctrine, because there is no USA.
1826: Brazil and Spain make a deal to split the Río de la Plata between them. Spain (with British help) joins the war against the unrecognised Río de la Plata.
1827: War of the Río de la Plata ends with Spain and Brazil each taking a part of the Río de la Plata. Spain's section is reorganised into the Viceroyalty of the Río de la Plata.
1828: In Greece, the Republic of Greece gains de facto independance from Ottoman rule, though the war is not yet over. Ioannis Kapodistrias is elected Governor. Kapodistrias begins reforming and modernising Greece.
1830: Greek War of Independance ends with Greek victory, with some British, French and Russian help.
1831: Greek governor Ioannis Kapodistias is not assassinated. Kingdom of Greece is not formed.