Napoleon's army carried out excavations during its Egyptian campaign, in 1798–1801, which also was the first major overseas archaeological expedition. The emperor took with him a force of 500 civilian scientists, specialists in fields such as biology, chemistry and languages, in order to carry out a full study of the ancient civilisation. The work of Jean-François Champollion in deciphering the Rosetta stone to discover the hidden meaning of hieroglyphics proved the key to the study of Egyptology.