Final answer:
Napoleon Bonaparte became Emperor of France in 1804 after being declared Consul for Life in 1802, and Louis Napoleon, his nephew, declared himself as Napoleon III in 1852 following a coup.
Step-by-step explanation:
Napoleon Bonaparte, after a steady rise to power, eventually assumed the title of Emperor of France. His ascent began in 1799 with a successful coup d'etat, leading to the establishment of the Consulate where he was a consul. He dominated the government and was declared Consul for Life in 1802. Through continuous conquests and reforms, he bolstered his position and was elected emperor by the French senate in May 1804. Napoleon crowned himself on December 2, 1804, at Notre Dame in Paris, symbolically following in the footsteps of Charlemagne and embracing the traditions of French monarchy. Additionally, his nephew Louis Napoleon, emulating his uncle's path, declared himself as Napoleon III after staging a coup in 1852.