By the turn of the 20th century, fears had begun to grow in Britain that it would no longer be able to defend the metropole and the entirety of the empire while at the same time maintaining the policy of "splendid isolation". Germany was rapidly rising as a military and industrial power and was now seen as the most likely opponent in any future war. Recognising that it was overstretched in the Pacific and threatened at home by the Imperial German Navy, Britain formed an alliance with Japan in 1902 and with its old enemies France and Russia in 1904 and 1907, respectively.

Which country seemed like Britain's most likely threat in the early 20th century?