Ben-Gurion was living in Jerusalem at the start of the First World War, where he and Ben Zvi recruited forty Jews into a Jewish militia to assist the Ottoman Army.
Despite this he was deported to Egypt in March 1915.
From there he made his way to the United States where he remained for three years.
On his arrival he and Ben Zvi went on a tour of 35 cities in an attempt to raise a pioneer army, Hechalutz, of 10,000 men to fight on Turkey's side.

After the Balfour Declaration of November 1917, the situation changed dramatically and in 1918 Ben-Gurion, with the interest of Zionism in mind, switched sides and joined the newly formed Jewish Legion of the British Army.
He volunteered for the 38th Battalion, Royal Fusiliers, one of the four which constituted the Jewish Legion.
His unit fought against the Turks as part of Chaytor's Force during the Palestine Campaign, though he remained in a Cairo hospital with dysentery.

Ben-Gurion and his family returned permanently to Palestine after World War I following its conquest by the British from the Ottoman Empire.
Ben-Gurion was living in Jerusalem at the start of the First World War, where he and Ben Zvi recruited forty Jews into a Jewish militia to assist the Ottoman Army. Despite this he was deported to Egypt in March 1915. From there he made his way to the United States where he remained for three years. On his arrival he and Ben Zvi went on a tour of 35 cities in an attempt to raise a pioneer army, Hechalutz, of 10,000 men to fight on Turkey's side.
After the Balfour Declaration of November 1917, the situation changed dramatically and in 1918 Ben-Gurion, with the interest of Zionism in mind, switched sides and joined the newly formed Jewish Legion of the British Army. He volunteered for the 38th Battalion, Royal Fusiliers, one of the four which constituted the Jewish Legion. His unit fought against the Turks as part of Chaytor's Force during the Palestine Campaign, though he remained in a Cairo hospital with dysentery.
Ben-Gurion and his family returned permanently to Palestine after World War I following its conquest by the British from the Ottoman Empire.
David Ben-Gurion