<Tr> <Th> Adopted </Th> <Td> October 1921 (modified June 24, 1937) </Td> </Tr> <Tr> <Th> Design </Th> <Td> Horizontal bicolour of blue and red; charged with a gold crown in the canton </Td> </Tr> <P> The flag of Liechtenstein (German: Flagge Liechtensteins) consists of two horizontal blue and red bands charged with a gold crown at the canton . Adopted in 1921 after being officially enshrined into the nation's constitution, it has been the flag of the Principality of Liechtenstein since that year . The crown was added to the flag in 1937 after the country found out at the Summer Olympics held the previous year that their flag was identical to the flag of Haiti . </P> <P> Liechtenstein was formed in 1719 as a principality within the Holy Roman Empire, and gained complete independence in 1866 . Within this period, the colours blue and red were selected to feature on the flag, instead of the gold and red on the coat of arms that would have customarily been employed instead . These new livery colours were first utilized by Prince Joseph Wenzel I in 1764 . </P>

What event led to liechenstein adding a crown to its flag
find me the text answering this question