Maria Isabela's life was deeply marked by Napoleon's actions. Fearing for his crown, King Ferdinand joined the Third Coalition against Bonaparte. Napoleon’s troops defeated the allied armies at the Battle of Austerlitz in December 1805 and the Neapolitan corps at Campo Tenese. Following these victories, Napoleon's forces occupied Naples in 1806. The Emperor gave the crown of Naples to his brother Joseph Bonaparte, and four years later to his brother-in-law Joachim Murat.