Upon the establishment of the First French Empire, he was made one of the original eighteen Marshals of the Empire. In 1805, he fully regained Napoleon's favour, which he lost during the consulate. At Austerlitz, he commanded the left wing of the "Grande Armée". During the War of the Fourth Coalition, Lannes was at his best, commanding his corps with the greatest credit in the march through the Thuringian Forest, the Battle of Saalfeld (which is studied as a model today at the French Staff College), and the Battle of Jena. His leadership of the advance guard at Friedland was even more prominent.