The pictorial satire of William Hogarth is regarded as a precursor to the development of political cartoons in 18th century England. George Townshend produced some of the first overtly political cartoons and caricatures in the 1750s. The medium began to develop in the latter part of the 18th century under the direction of its great exponents, James Gillray and Thomas Rowlandson, both from London. Gillray explored the use of the medium for lampooning and caricature, and has been referred to as the father of the political cartoon. By calling the king, prime ministers and generals to account for their behaviour, many of Gillray's satires were directed against George III, depicting him as a pretentious buffoon, while the bulk of his work was dedicated to ridiculing the ambitions of revolutionary France and Napoleon. George Cruikshank became the leading cartoonist in the period following Gillray, from 1815 until the 1840s. His career was renowned for his social caricatures of English life for popular publications.