Write a question about the following article: The military aspect of the war began with the Armistice of Mudros. The military operations of the Greco-Turkish war can be roughly divided into three main phases: the first phase, spanning the period from May 1919 to October 1920, encompassed the Greek Landings in Asia Minor and their consolidation along the Aegean Coast. The second phase lasted from October 1920 to August 1921, and was characterised by Greek offensive operations. The third and final phase lasted until August 1922, when the strategic initiative was held by the Turkish Army.

Question about the article:
How many months did the first phase of the war last?