Bulgarian intervention against Serbia meant more than an additional congregation of strength on her eastern flank, it effectively cut her supply lines from Salonika. Her army now looked to Italy to ship vital supplies across the Adriatic from her southeastern ports to Albania. Early in December, Austrian ships mounted a raid on two Italian supply ports. In the weeks that followed a naval war developed in which Allied shipping was attacked not only by the Austrians but by German U-boats.

This article is located in the History of the First World War Volume 3 (REF D522 .H58 1969 V.3).