In 1851 Great Britain was probably the leader of the industrial revolution and felt very safe about this status. The Great Exhibition in London, in 1851 was planned to symbolize this industrial, military and economic superiority of Great Britain.
I think it would sound better (and more attuned to the English grammar rules) the following way: "The Great Exhibition in 1851 in London was planned to symbolize this industrial, military and economic superiority of Great Britain."
By the way, the D in "and" is omitted...