All the dealings were secret, and Berlin and Vienna did not realize it had lost an ally. As a consequence, when the First World War broke out in July 1914, Italy announced the Triple Alliance did not apply, declared itself neutral, and negotiated the best deal available. Britain and France thought Italian military manpower would be an advantage, and offered Italy large swaths of territory from Austria and the Ottoman Empire. Italy eagerly joined the Allies in early 1915. Both countries were among the "Big Four". Italy took part in the Second Battle of the Marne and the subsequent Hundred Days Offensive in the Western Front, while few French soldiers took part in the Battle of the Piave River and the Battle of Vittorio Veneto in the Italian front. Reaction in Italy to the difference between the promises of 1915 and the actual results of the 1919 Treaty of Versailles and Entente betrayal was extremely negative; the intense dissatisfaction, mobilized by veterans, led to the takeover of the Italian government by Fascists led by Benito Mussolini.