After 26 February 1917, when an Anglo-French Congress at Calais decided on a spring offensive, Murray received strong encouragement. The decision by the Supreme War Council was given increased impetus for "Allied activity" on 8 March when the Russian Revolution began. By 11 March Baghdad in Mesopotamia had been occupied by British Empire forces, and an offensive in Macedonia had been launched. In April the Battle of Arras was launched by the British, and the French launched the Nivelle offensive. Britain's three major war objectives now were to maintain maritime supremacy in the Mediterranean Sea, while preserving the balance of power in Europe and the security of Egypt, India, and the Persian Gulf. The latter could be secured by an advance into Palestine and the capture of Jerusalem. A further advance would ultimately cut off the Ottoman forces in Mesopotamia from those on the Arabian Peninsula and secure the region.