Between 1815 and 1914, a period referred to as Britain's "imperial century" by some historians, around 10,000,000 square miles (26,000,000 km2) of territory and roughly 400 million people were added to the British Empire. Victory over Napoleon left Britain without any serious international rival, other than Russia in central Asia. Unchallenged at sea, Britain adopted the role of global policeman, a state of affairs later known as the Pax Britannica, and a foreign policy of "splendid isolation". Alongside the formal control it exerted over its own colonies, Britain's dominant position in world trade meant that it effectively controlled the economies of many countries, such as China, Argentina and Siam, which has been characterised by some historians as "Informal Empire".

How many square miles of territory were added to the British Empire between 1815 and 1914?