The British Empire was at its largest in 1919. At this point, there was truth in the saying that the Sun never set on the British Empire. 

The British Empire was at its largest in 1919, after Britain acquired Germany’s East and West African colonies and Samoa in the Treaty of Versailles, which marked the end of the First World War, 1914–18.

At that point it was literally true that the Sun never set on the British Empire: during a 24-hour day there was never a moment at which it was not daylight somewhere in Britain’s territories.

It was also claimed that at its height the British Empire covered a quarter of the Earth’s surface. However, this figure is only correct if countries that were under formal protection agreements, rather than being a part of empire, are included.

It is also true that the Empire began to shrink virtually as soon as it reached its greatest extent. Only three years later in 1922, Ireland and Egypt gained their independence.