In 1900 the place was rebuilt due to an outbreak of plague. Later in 1907, Nairobi turned into a commercial center and became the capital of the British East Africa by replacing Mombasa. Nairobi flourished under the British rule and also became a home for many Britons. In 1919, the British declared Nairobi as a municipality. In 1921, Harry Thuku established the Young Kikuyu Association and began organizing protests against the British. Harry Thuku was arrested on 14th March 1922. There was a general strike by thousands of Africans in Nairobi and the British government started shooting the Protestants. The Massacre shocked people worldwide, along with the British.