The Walcheren Campaign was an unsuccessful British expedition to the Netherlands in 1809 intended to open another front in the Austrian Empire's struggle with France during the War of the Fifth Coalition. Sir John Pitt, 2nd Earl of Chatham, was the commander of the expedition, with the missions of capturing Flushing and Antwerp in the Netherlands and enabling navigation of the Scheldt River. Some 39,000 soldiers and 15,000 horses, together with field artillery and two siege trains, crossed the North Sea and landed at Walcheren on 30 July. This was the largest British expedition of that year, larger than the army serving in the Peninsular War in Portugal. Nevertheless, it failed to achieve any of its goals. The Walcheren Campaign involved little fighting, but heavy losses from the sickness popularly dubbed "Walcheren Fever". Although more than 4,000 British troops died during the expedition, only 106 died in combat; the survivors withdrew on 9 December.

The Kingdom of Holland was the successor state of the Batavian Republic. It was created by Napoleon Bonaparte in March 1806 in order to strengthen control over the Netherlands by replacing the republican government with a monarchy. Since becoming emperor in 1804, Napoleon sought to extirpate republican tendencies in territories France controlled, and placed his third brother, Louis Bonaparte, on the throne of the puppet kingdom. The name of the leading province, Holland, now designated the whole country. In 1807, East Frisia and Jever were added to the kingdom.