As Serbia was invaded by the armies of Germany, Austria-Hungary and Bulgaria, a British and French force advanced from Salonika in Greece to provide some assistance. Unfortunately the might of the Bulgarians has proved too much for the ineffectual Allied force. At Krivolak the French were defeated and at Kosturino the British too were obliged to retreat. Now the Allies are back in Greece, but showing no sign of going home, much to the annoyance of Greece’s King Constantine, who wants to keep his country out of the war.
The Bulgarians are keen to cross the Greek border and attack the British and French. They would probably like to annex Salonika while they are at it, as they feel this unfairly ended up with the Greeks after the recent Balkan Wars of 1912 and 1913. But Germany’s Falkenhayn forbids an advance across the Greek frontier. He fears that a Bulgarian invasion would be enough of a provocation to bring Greece into the war on the side of the Allies. Better to leave the Allies to fester in Salonika where they can do no harm.
image source (Wikipedia)