In 1806 Napoleon, Emperor of the French, decided to place his brother Joseph Bonaparte on the Neapolitan throne. Some 32,000 French troops invaded Naples in January, in three columns under General Laurent de Gouvion-Saint-Cyr, later a Marshal of France; about 12,000 men marched down the Adriatic coast, 15,000 more attacked down the Apennines, which form the spine of Italy, and General Jean Louis Reynier led about 10,000 troops down the Appian Way. The Neapolitan Army, with barely 13,000 men available for mobile operations, fell back on Calabria as the French quickly occupied frontier areas and pressed on. By February Reynier's column had captured Fondi and continued on towards Itri. Some Neapolitan troops were garrisoned at Pezza's old base, the "Fortino di San Andrea,", but they fled south to Itri when the French turned up. The French pursued. There was a short skirmish at Itri, which hardly impeded the French advance. Reynier sent a regiment ahead to seize Gaeta by a "coup de main", but the fortress, commanded by Louis, Landgrave of Hesse-Philippsthal, resisted stoutly. The Siege of Gaeta lasted until 18 July. The French found the rest of Naples easier prey. The capital fell on 14 February as the king and queen once more fled to Sicily, and the French soon overran most of the rest of the kingdom.