Complex sentence: Matthews declared that William Pitt was "not half" susceptible to these attacks and held that these gangs were responsible for the British military disasters at Buenos Aires in 1807 and Walcheren in 1809 and also for the Nore Mutiny of 1797.
Split into simpler sentences: Matthews declared that William Pitt was "not half" susceptible to these attacks. Matthews held that these gangs were responsible for the British disasters at Buenos Aires in 1807 and Walcheren in 1809 and also for the Nore Mutiny of 1797.