Desertions from the armed forces of Middle East countries—both by high ranking Arab officers and by soldiers-form a chapter of their own. Desertion was repeatedly urged in Nazi radio and leaflet propaganda and by the Fifth Column in each country.The Arab leaders in Germany vigorously propagandized against enlistment of Arabs in the British Army. This, as it happened, was hardly necessary. So few Palestine Arabs joined the Army that Syrians, Lebanese and Transjordanians were encouraged to cross into Palestine and enlist as Palestinians, to fill the quota fixed for Palestine Arab units. It will be recalled that Jewish enlistment in parallel Jewish infantry units was held down to the Arab rate-a rather peculiar service to the war effort on the part of the Palestine Administration. It took the steadily · worsening military situation in the Middle East and the continued pressure by Jewish volunteers to break down this attempt at "equality.” In all, as the Secretary of State for War stated in the 18 Al-Bilad of May 28, 1941, House of Commons on April 2, 1945, 25,714 Palestinian Jews served in the British Forces and 9,041 Arabs.Many Arab soldiers from Palestine went over to the enemy. The Germans had some success with the help of Arab leaders in mobilizing recruits for their Arab brigades from among Palestinian Arab prisoners of war. In the liberation of Europe Allied forces took prisoner a number of Arabs in German uniform, who had formerly been soldiers in the British Army.Apart from desertions to the enemy, there were many hundreds of cases of ordinary desertion by Arab soldiers, some of whom left their units with their arms. At least half the Arab soldiers who joined up in Palestine disappeared from the ranks of the British Army through desertion or through discharge on the ground that they were unfit for service.
I was unaware that initially Britain actually limited the number of Palestinian Jews who could volunteer for the army to keep things "equal."
The Palestine Post quotes some of the arguments in British Parliament for and against allowing Jews to fight for the Allied war effort in 1942, with some pre-emptively blaming Jews fighting with the British for Arab support for Nazi Germany.
(h/t Daniel)