Rouget began his professional career as his master's main assistant until David's exile to Brussels, collaborating with him on the canvases Bonaparte at the Grand-Saint-Bernard, The Coronation of Napoleon (of which he made a copy signed by David), Leonidas at Thermopylae and on one of the three copies of the Portrait of Pope Pius VII. Though winning the second prize in the prix de Rome contest in 1803, he failed three times to win the first prize. He produced many canvases for the First French Empire and the Bonapartes, such as The Marriage of Napoleon and Marie Louise in 1811.