was largely ineffective and did little economic damage to Great Britain. Both sides entered further conflicts in attempts to enforce their blockade. As Napoleon realised that extensive trade was going through Spain and Russia, he invaded those two countries.; the British fought the United States in the War of 1812 (1812–1815). In 1810, the French Empire reached its greatest extent. Napoleon married Marie-Louise, an Austrian Archduchess, with the aim of ensuring a more stable alliance with Austria and of providing the Emperor with an heir (something his first wife, Josephine, had failed to do). As well as the French Empire, Napoleon controlled the Swiss Confederation, the Confederation of the Rhine, the Duchy of Warsaw and the Kingdom of Italy. Territories allied with the French included: the Kingdom of Denmark the Kingdom of Spain (under Joseph Bonaparte, Napoleon's elder brother) the Kingdom of Westphalia (Jérôme Bonaparte, Napoleon's younger brother) the Kingdom of Naples (under Joachim Murat, husband of Napoleon's sister Caroline) the Principality of Lucca and Piombino (under Elisa Bonaparte (Napoleon's sister) and her husband Felice Baciocchi); and Napoleon's former enemies, Sweden, Prussia and Austria. Subsidiary wars The Napoleonic Wars were the direct cause of wars in the Americas and elsewhere. War of 1812 The War of 1812 coincided with the War of the Sixth Coalition. Historians in the United States and Canada see it as a war in its own right, while Europeans often see it as a minor theatre of the Napoleonic Wars. The United States declared war on Britain because of British interference with American merchant ships and forced enlistment into the Royal Navy. France had interfered as well, and the United States considered declaring war on France. The war ended in a military stalemate, and there were no boundary changes at the Treaty of Ghent, which took effect in early 1815 when Napoleon was on Elba. Latin American Revolutions The abdication of Kings Carlos IV and Fernando VII of Spain and the installation of Napoleon's brother as King José provoked civil wars and revolutions leading to the independence of most of Spain's mainland American colonies. In Spanish America many local elites formed juntas and set up mechanisms to rule in the name of Ferdinand VII, whom they considered the legitimate Spanish monarch. The outbreak of the Spanish American wars of independence in most of the empire was a result of Napoleon's destabilizing actions in Spain and led