In 1921 Britain created Trans-Jordan and gave it to the
Hashemites to rule over. Trans-Jordan is an arbitrary piece of
the Arabian desert and Churchill famously boasted that he had created
it with "a stroke of his pen" on a Sunday afternoon. Syria
considered Jordan to be part of Southern Syria. Ibn Saud, king
of Saudi Arabia, considered the territory part of his kingdom. On
the other hand, the Hashemite king Abdullah made no secret of his
plans to expand his kingdom. Hence, Trans-Jordan's standing on the
international scene was precarious and greater cooperation with the
Zionists in Palestine became logical.
King Abdullah and Golda Meir of the Jewish Agency had a secret meeting
in the middle of November 1947. There, they outlined a general
strategy for the upcoming war in Palestine that they both knew were
inevitable. A few days later the UN General Assembly would recommend
that Palestine be partitioned into a Jewish and an Arab state, against
the wishes of its population. According to Yaacov Shimoni of the
Jewish Agency, who Shlaim cites:
We would agree to the conquest of the Arab part of Palestine by
Abdullah. We would not stand in his way. We would not help him,
would not seize it and hand it over to him. He would have to take it
by his own means and stratagems but we would not disturb him. He,
for his part, would not prevent us from establishing the state of
Israel, from dividing the country, taking our share and establishing
a state in it.
Meir and Abdullah met again in May 1948, days before Israel
declared independence. There he lamented the circumstances that forced
his hand, "I am one among five. I have no alternative [but to declare
war], and I cannot act otherwise" Meir reported back to the Mapai
Central Committee:
We met [on 10 May] amicably. He is very worried and looks
terrible. He did not deny that there had been talk and understanding
between us about a desirable arrangement, namely that he would take
the Arab part [of Palestine]...."
But the agreement with the Zionists held; his Arab Legion would not
enter territory earmarked for the Jewish State.
The supreme commander of the Arab Legion was Glubb Pasha, a British
officer tasked with implementing the Jordanian part of the
agreement. He discussed the parties' plans for Palestine in a meeting
with the British Foreign Secretary, Ernest Bevin, in London in
February 1948:
The situation envisaged by us and by H.M.G. when we were in London,
was that nothing much would happen until May 15th. The Jews would
then implement the Jewish state, with the blessing of a united
U.N.O., and the Arab areas of Palestine would be a vacuum, into
which the Arab Legion would march.
Throughout the war the alliance mostly held; the Arab Legion and the
Haganah/IDF avoided battling each other. Jerusalem which had been
allotted to an international zone was the major exception. Glubb
suspected that the Zionists would certainly try to capture the whole
city for themselves. Abdullah was also subjected to repeated pleas to
save the Arabs of Palestine. Thus, he ordered Glubb to take the Arab
Legion into Jerusalem and Glubb reluctantly accepted. However,
the Arab Legion only occupied the Old City and Arab parts of Jerusalem - the Jewish colony in west Jerusalem was left alone.
Counterpoint Israeli and Jordanian units fought each other so
there couldn't have been an alliance.
This a bogus argument since by the same logic the Molotov-Ribbentrop
Pact couldn't have existed since the heaviest fighting of the
Second World War was on the eastern front between the Germans and the
Soviets. Tactical considerations, fog of war, politics, and other
factors explain perfectly well why Israeli and Jordanian units clashed despite the agreement.