At the commencement of the War of the Fifth Coalition in 1809 he became commander of the Army of Inner Austria, fighting against the French forces of Eugène de Beauharnais in Italy. Under his command were the VIII Armeekorps led by Albert Gyulai and the IX Armeekorps headed by Albert's brother Ignaz Gyulai. After winning a significant victory at the Battle of Sacile on 16 April 1809, his army advanced almost to Verona. Having detached forces to besiege Venice and other fortresses, John's army was soon outnumbered by Eugène's heavily reinforced host. Worse, news of the Austrian defeat at the Battle of Eckmühl reached him and compelled him to order a retreat. Before withdrawing, he fought off Franco-Italian attacks at the Battle of Caldiero between 27 and 30 April. Attempting to blunt the Franco-Italian pursuit, he stood to fight on 8 May and was beaten at the Battle of Piave River. Trying to defend the entire border, he sent Ignaz Gyulai to defend Ljubljana (Laibach) in Carniola, while holding Villach in Carinthia with his own forces. Eugène's pursuit overran the frontier defenses at the Battle of Tarvis and wrecked a column of hoped-for reinforcements at the Battle of Sankt Michael. Forced to flee northeast into Hungary, John offered battle again but was defeated at Raab on 14 June 1809. Ordered to join his brother Archduke Charles at the Battle of Wagram on 5 and 6 July, John's small army arrived too late to avert an Austrian defeat. His brother criticized him for tardiness.