First given earthworks in 1779 against the planned invasion that year, the high ground west of Dover, England, now called Dover Western Heights, was properly fortified in 1804 when Lieutenant-Colonel William Twiss was instructed to modernise the existing defences. This was part of a huge programme of fortification in response to Napoleon's planned invasion of the United Kingdom. It followed a sustained period of related work by Twiss on upgrading the fortifications of nearby Dover Castle (1794–1803).