The historian Dan Schwartz explains the largely forgotten—and monumental—effects of World War I on Jewish history, including the mass participation of Jewish soldiers in the fighting and the conflict’s impact on Zionism:
In the debates about granting Jews [legal] equality, which dated back to before the French Revolution, the question was, “Can we really trust Jews to be good soldiers? Can we really trust them to be patriots?” The argument was made that, “Look, Jews will be more loyal to their fellow Jews than they will be to people in this particular nation.” World War I certainly is not the first time that Jews fought on opposite sides. . . . In the American Civil War, Jews fought for both sides, as they did early in the 19th century in the various Napoleonic wars. But on nothing approaching this scale.
World War I was [also] a turning point . . . because two of the most significant events of the Jewish 20th century—the Holocaust and the creation of the state of Israel—are almost unimaginable without World War I.
By the second decade of the 20th century, modern anti-Semitism, which had emerged in the late 19th century, seemed, for the most part, to have petered out as a political movement. But World War I gave it new life. The German experience in the war—its defeat, its [perceived] humiliation by the Allies, and the scapegoating of Jews for the economic, social, and political turmoil that followed—set in motion the events leading to the Holocaust.
Similarly, Zionism was a late-19th-century movement that as of 1914 seemed to have run into a brick wall. The Ottoman empire was implacably opposed to Zionism, basically preventing Zionists from immigrating, [or] at least from purchasing land. Even though the war itself was initially damaging to Zionism and to the [early Jewish settlers of Palestine], the alliance [with Britain] and the Balfour Declaration that came from it enabled the movement to develop. This is something that could not have been anticipated [prior to the outbreak of war] in 1914.
Read more on Moment: http://www.momentmag.com/how-the-first-world-war-changed-jewish-history/