detached troops to support Charles. John won victory at the 30 April Battle of Caldiero but was forced to retreat due to Eugène's increasing superiority and the movements on the Austria-Bavaria front. John was defeated in the 8 May Battle of Piave River and forced out of Italy. Eugène detached MacDonald to pursue John and joined Napoleon at Vienna with the rest of his army. In the Dalmatian Campaign, Marmont, under the nominal command of Eugène, was fighting against an Austrian invasion led by General Stoichewich. Marmont launched a counteroffensive in the mountains on 30 April, but this was repulsed by the Grenzer troops. Further attacks in May led to a series of victories against a dispersed Austrian force. By the end of the month Marmont was able to march with the bulk of his troops to join the emperor at Vienna. Failed British feint operation In July 1809 the British launched the Walcheren Campaign in the Netherlands to relieve the pressure on the Austrians and to weaken French naval power. The plan was to land a force at Walcheren and advance along the Western Scheldt to the harbour of Antwerp, a French naval base. The Royal Navy's patrols into the Western Scheldt and a dockyard strike at Antwerp alerted the French to the area's vulnerability and efforts were made to improve the defences and reinforce its garrisons. John Pitt, 2nd Earl of Chatham's force of over 39,000, a larger army than that serving in the Iberian Peninsula and the largest British Expeditionary Force of the Napoleonic Wars, landed at Walcheren on 30 July. The expedition was not capable of landing sufficient troops on the southern side of the Western Scheldt to capture the reinforced garrison at Cadzand due to a lack of boats. An advance on Antwerp depended on the capture of Flushing on the northern shore to allow the passage of Royal Navy vessels up the Western Scheldt. It took until 13 August for siege batteries to be set up and Flushing did not surrender until 16 August. The British forces had meanwhile been suffering from "Walcheren Fever", thought to be a combination of Malaria and Typhus, and lost 4,000 men to the disease during the campaign. By comparison only 106 men were killed in action. By 24 August Chatham had decided that the fever had reduced his force too much and the defences of Antwerp were too