Multiple choice general knowledge history By which year did Napoleon's armies conquer almost the whole of Europe? 1817 1870 1800 1807 Reveal answer Fill a bubble to check yourself D Correct answer Explanation By 1807, Napoleon achieved military dominance after Austerlitz (1805), Jena-Auerstedt (1806), and the Treaty of Tilsit. His decline began with the 1812 Russian campaign, and by 1817 he was exiled on St. Helena.