Overview: While the US breaks of diplomatic relations with Germany in response to unrestricted submarine warfare, the Western Front is rather quiet. On the Macedonian Front, the Bulgarian Army is digging in at Doiran. They built a formidable defence network without the Entente realising it and this week 100 years ago the British get a first taste of that. The British also deal the final blow against the Senussi tribesmen on the Libyan Front.