Simplify the following text for a Grade 7 native English-speaking person.
Original: He was the principal organiser of the first international chess tournament in 1851 , which made England the world 's leading chess center and caused Anderssen to be recognized as the world 's strongest player .
Simplified: These events helped to make London the world 's leading chess center . The winner of the tournament , Anderssen , became recognized as the world 's strongest player .