 In August 1785 Cornwallis attended manoeuvres in Prussia along with the Duke of York where they encountered Frederick the Great and Cornwallis 's Virginia opponent , the marquis de Lafayette . In 1786 he was appointed to be Commander @-@ in @-@ Chief of British India and Governor of the Presidency of Fort William , also known as the Bengal Presidency . He served in these posts with distinction , enacting administrative reforms in the British East India Company , and made changes to judicial , civil , and revenue administration in the company 's territories that had significant long @-@ term consequences . He returned to England in 1794 , worn out from the difficult military campaigns of the Third Anglo @-@ Mysore War , in which he led the first major British defeat of Tipu Sultan . 
