Britain secretly agrees to back Japan’s claim to the islands; France and Russia later approve.

What happened

Until 1917 no major Allied government recognized Japan’s hold on the islands. Britain agreed to support Japan’s claims at the coming peace conference only after Japan promised naval escorts for Allied shipping in the Pacific and the Mediterranean; France and Russia then approved the secret deal.

Why it matters

This agreement left the 1919 peace conference facing what a 1948 US Navy handbook called a fait accompli.