Napoleon
In the Kingdom of Holland, the British launched the Walcheren Campaign to open up a second front in the war and to relieve the pressure on the Austrians. The British army only landed at Walcheren on 30 July, by which point the Austrians had already been defeated. The Walcheren Campaign was characterized by little fighting but heavy casualties thanks to the popularly dubbed "Walcheren Fever." Over 4000 British troops were lost in a bungled campaign, and the rest withdrew in December 1809. The main strategic result from the campaign became the delayed political settlement between the French and the Austrians. Emperor Francis wanted to wait and see how the British performed in their theater before entering into negotiations with Napoleon. Once it became apparent that the British were going nowhere, the Austrians agreed to peace talks.

Q: The Walcheren Campaign was intended to relieve the military pressure on whom?
the Austrians