Answer:
The best answer to the question: Why does MacGregor begin the chapter on the slit drum with facts about Horatio Herbert Kitchener, would be: To make the reader wonder how the slit drum helped make Kitchener famous.
Explanation:
"A History of The World in 100 Objects" is both a radio program from the BBC, and a book from British Museum´s directior, Neil MacGregor in which, through a selected group of 100 objects present in the Museum, the history of the world is told and joined together. It is of great interest the way that MacGregor not only narrates about these wonderful objects, all of which ended up in British hands, but also the span of history they portray, showing the importance of the hand of England in maintaining such historical artifacts.
MacGregor also ties each of the objects to historical moments and characters in English history, and one such object is the slit drum, an artifact from Sudan that was found and presented to Queen Victoria by Horatio Herbert Kitchener.
The tying of these two: the historical slit drum, and Kitchener allow the reader of MacGregor´s book not only wonder, but guess, how such an artifact, that could still not be dated when Kitchener found it, give him such fame. He could not have known then that what had been discovered, marked such an important historical moment and that he would become a central figure.