In the following year, 1697, Mustapha again marched with his army from Belgrade into Hungary, without any definite plans as to what he proposed to do. After many councils of war and much irresolution, it was decided to advance northwards to the River Theiss. The Austrian army was now under command of Prince Eugène of Savoy, who, we have seen, made his début at the siege of Vienna. He was the ablest general of his time. The two armies met at Zenta on the River Theiss, about sixty miles above its junction with the Danube. The Turks had erected a bridge over the river at this point. The Sultan and his cavalry, and a great part of the artillery, had already crossed the bridge. The infantry were still on the other side. Prince Eugène with his army, coming suddenly upon them, caught the Turkish army _in flagrante delicto_, divided by the river. Advancing in a wide crescent, he attacked the whole line of the Ottoman infantry who had not crossed the river. There was great confusion in the ranks of the Ottomans and discord among the leading officers and a want of direction. A large body of Janissaries mutinied on the field of battle and began to massacre their officers. There ensued an overwhelming defeat of the Ottomans. Twenty-six thousand Turks were slain on the battlefield and ten thousand were drowned in their attempt to cross the river. The Grand Vizier, four other viziers, and a great number of pashas and thirty aghas of Janissaries were killed; four hundred and twenty standards were captured. The Sultan, who had witnessed the battle from the other side of the river in comparative safety, was able to escape with some of his cavalry to Temesvar, and thence he returned to Belgrade and Constantinople. This experience satisfied his military ardour, and he never again appeared at the head of his army. An immense booty fell into the hands of the Austrians. All the Turkish guns were captured. What remained of the army defeated at Zenta found its way to Belgrade, and thence returned to Adrianople, while Prince Eugène crossed the Danube into Bosnia and made himself master of the greater part of that province. This great victory of the Austrians, after fourteen years of almost uninterrupted success, decided not only the campaign but the war in their favour, and marked irrevocably the decadence of the military power of the Ottoman Empire. Six days after the battle the Sultan, in his peril, turned once more to the Kiuprili family for help. In place of the Grand Vizier, who had been killed at Zenta, he appointed Hussein Kiuprili, a son of the elder brother of Mahomet Kiuprili, and therefore a cousin of Ahmed. Until the siege of Vienna he had given himself up to a life of pleasure, but after that grave defeat of the Turks he filled with great distinction many high posts in the government. He was the fourth member of his family to hold the position of Grand Vizier, and showed himself fully capable of bearing the burden.