Why did Britain restrict Jewish immigration to Palestine in 1939?

In 1939, the British government issued a white paper that severely restricted Jewish immigration to Palestine, limiting it to 75,000 people over the following five years, after which further immigration would require Arab "acquiescence".1

This policy shift was driven by several strategic and political factors:

• Regional Stability and War Concerns: As the prospect of World War II loomed, the British government feared that continued large-scale Jewish immigration would incite further hostility from the Arab population in Palestine and neighboring countries. Britain sought to retain Arab support against the threat of Germany and Italy.2
• The Arab Revolt: The 1936–39 Arab Revolt had placed immense strain on British governance. The uprising, fueled by opposition to Zionist immigration and land purchases, forced Britain to reassess its mandate policies to quell the violence and restore order.312
• Failure of Partition: Previous attempts to resolve the conflict through the partition of Palestine, such as those proposed by the Peel Commission, were rejected by both Arabs and Jews, leaving Britain to seek a new policy that might appease the Arab majority.12