The British Empire was the largest empire in history.
Why it is true
At its peak in 1920, it controlled about a quarter of the Earth's surface and world population.
Source: Oxford University
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.