After World War I, the British and the French empires replaced the Ottoman Empire as the preeminent powers in the Middle East.
This change brought closer the Zionist Movement's goal of creating a Jewish state.
The Balfour Declaration of 1917 indicated that the British Government supported the creation of a Jewish homeland in Palestine in principle, marking the first official support for Zionist aims.
It led to a surge of Jewish emigration in 1918–1921, known as the "Third Aliyah".
The League of Nations incorporated the Declaration in the British Mandate for Palestine in 1922.
Jewish immigration continued through the 1920s and 1930s, and the Jewish population expanded by over 400,000 before the beginning of World War II.

In 1939, however, the British Government of Neville Chamberlain appeared to reject the Balfour Declaration in the White Paper of 1939, abandoning the idea of establishing a Jewish Dominion.
When the United Kingdom declared war on Nazi Germany in September 1939, David Ben-Gurion, the head of the Jewish Agency, famously declared: "We will fight the White Paper as if there is no war, and fight the war as if there is no White Paper."
After World War I, the British and the French empires replaced the Ottoman Empire as the preeminent powers in the Middle East. This change brought closer the Zionist Movement's goal of creating a Jewish state. The Balfour Declaration of 1917 indicated that the British Government supported the creation of a Jewish homeland in Palestine in principle, marking the first official support for Zionist aims. It led to a surge of Jewish emigration in 1918–1921, known as the "Third Aliyah". The League of Nations incorporated the Declaration in the British Mandate for Palestine in 1922. Jewish immigration continued through the 1920s and 1930s, and the Jewish population expanded by over 400,000 before the beginning of World War II.
In 1939, however, the British Government of Neville Chamberlain appeared to reject the Balfour Declaration in the White Paper of 1939, abandoning the idea of establishing a Jewish Dominion. When the United Kingdom declared war on Nazi Germany in September 1939, David Ben-Gurion, the head of the Jewish Agency, famously declared: "We will fight the White Paper as if there is no war, and fight the war as if there is no White Paper."
Jewish Brigade