The first and largest wave of Palestinian refugees occured before May 14, 1948 the date of the Declaration of Independence and the arrival of the Arab armies on May 15, 1948 -- essentially in the wake of the Dir Yassin massacre on April 9, 1948 that was perpetrated by Lehi and Irgun with the Haganah's connivance and the unfolding of the Haganah's (the leading Zionist military force) Plan D and was on going at that time of and after. (page 31 - Avi Shlaim - The Iron Wall: Israel and the Arab world and numerous other sources) Certainly the vast majority of exiles occured before the end of of the 1948 War. But there were smaller waves of refugees afterwards.
this article by :
Fred M. Donner
Professor of Near Eastern History
The Oriental Institute
The University of Chicago
Chicago, Ill. link:
http://www.princeton.edu/~paw/web_exclusives/more/more_letters/letters_doran.html"By 1914, the population of Palestine was about 650,000. Of this, the Jewish population was about 80,000, or a little over 12 percent. Of the 88 percent remaining, 570,000 people, Israeli and non-Israeli scholars estimate that at least 550,000 were Palestinians (Christian or Muslim) who were descendants of families in Palestine already in the 1840s — or almost 85 percent of the total 1914 populaton of Palestine."
"As we see, most Palestinians of today can trace their ancestry to families who have been resident in Palestine for hundreds of years. The debate over immigration figures is, of course, merely part of the broader effort by Palestinians and Israelis to delegitimize each other by claiming the other side to be interlopers. Mr. Schell's evident desire to cast doubt on the historical roots of the Palestinians' claim to their land suggests that he has been taken in, like many other people, by such works as Joan Peters's tract "From Time Immemorial," which popularized for obvious political purposes the myth that many Palestinians were descendants of recent immigrants.Such a view is simply not supported by the evidence. "
http://www.princeton.edu/~paw/web_exclusives/more/more_letters/letters_doran.html ______________________
this article by world renowned Israeli hisorian Avi Shlaim of Oxford regarding transfer:
London Review of Books, 9 June 1994.
link to full article:
http://users.ox.ac.uk/~ssfc0005/It%20Can%20Be%20Done.html "While the ethics of transfer had never troubled Ben-Gurion unduly, the growing strength of the Yishuv eventually convinced him of its practical feasibility. On 12 July 1937, for instance, Ben-Gurion confided to his diary:
The compulsory transfer of the Arabs from the valleys of the proposed Jewish state could give us something which we never had ... a Galilee free from Arab population .... We must uproot from our hearts the assumption that the thing is not possible. It can be done.
The more Ben-Gurion thought about it, the more convinced he became that "the thing" could not only be done but had to be done. On 5 October 1937, he wrote to his son with startling candour:
We must expel Arabs and take their places ... and, if we have to use force - not to dispossess the Arabs of the Negev and Transjordan, but to guarantee our own right to settle in those places - then we have force at our disposal.
The letter reveals not only the extent to which partition became associated in Ben Gurion's mind with the expulsion of Arabs from the Jewish state but also the nature and extent of his territorial expansionism. The letter implied that the area allocated for the Jewish state by the Peel Commission will later be expanded to include the Negev and Transjordan. Like Vladimir Jabotinsky, the founder and leader of Revisionist Zionism, Ben-Gurion was a territorial maximalist. Unlike Jabotinsky, Ben-Gurion believed that the territorial aims of Zionism could best be advanced by means of a gradualist strategy.
When the UN voted in favour of the partition of Palestine on 29 November 1947, the struggle for Palestine entered its decisive phase. Ben-Gurion and his colleagues in the Jewish Agency accepted the partition plan despite deep misgivings about the prospect of a substantial Arab minority, a fifth column as they saw it, in their midst. the Palestinians rejected the partition plan with some vehemence as illegal, immoral and impractical. By resorting to force to frustrate the UN plan, they presented Ben-Gurion with an opportunity, which he was not slow to exploit, for extending the borders of the proposed Jewish state and for reducing the number of Arabs inside it. By 7 November 1949, when the guns finally fell silent, 730,000 persons, or 80 per cent of the Arab population of Palestine, had become refugees. "
link to full article:
http://users.ox.ac.uk/~ssfc0005/It%20Can%20Be%20Done.html___________________
And there is also a historic record of other Zionist:
Let me quote former Israeli Foreign Minister and Israeli historian Shlomo Ben-Ami from "Scars of War Wounds of Peace: the Israeli-Arab Tragedy", page 25-26
http://www.amazon.com/Scars-War-Wounds-Peace-Israeli-Arab/dp/0195181581/sr=1-1/qid=1166681762/ref=pd_bbs_sr_1/102-8701952-4352901?ie=UTF8&s=books"The idea of transfer of Arabs had a long pedigree in Zionist thought. Moral scruples hardly intervened in what was normally seen as a realistic and logical solution, a matter of expediency. Israel Zangvill, the founding father of the concept, advocated transfer as early as 1916. For as he said, ' if we wish to give a country to a people without a country, it is utter foolishness to allow it to be the country of two people...."
"The idea of transfer was not the intimate dream of only the activists and militants of the Zionist movement. A mass exodus of Arabs from Palestine was no great tragedy, according to Menachem Usishkink, a leader of the General Zionist. To him the message of the Arab Revolt was that coexistence was out of the question and it was now either the Arabs or the Jews, but not both. Even Aharon Zislong, a member of the extreme Left of the Zionist Labour movements, who during the 1948 war would go on record as being scandalized by the atrocities committed against the Arab population, saw no 'moral flaw' in transfer of the Arabs...But again, Ben Gurion's voice had always a special meaning and relevance. At a Zionist meeting in June 1938 he was as explicit as he could be. 'I support compulsory transfer. I don't see in it anything immoral.' But he also knew that transfer would be possible only in the midst of war, not in 'normal times.' What might be impossible in such times, he said 'is possible in revolutionary times.' The problem was, then, not moral, perhaps not even political,it was a function of timing, this meant war"
and from page 43:
" Benny Morris found no evidence to show 'that either the leaders of the Arab states or the Mufti ordered or directly encouraged the mass exodus'. Indeed Morris found evidence to the effect that the local Arab leadership and militia commanders discouraged flight, and the Arab radio stations issued calls to the Palestinians to stay put, and even to return to their homes if they had already left. True, there were more than a few cases where local Arab commanders ordered the evacuation of villages. But these seemed to gave been tactical decisions taken under very specific military conditions..."
From page 44:
"The first major wave of Arab exodus in April-May 1948, essentially in the wake of the Dir Yassin massacre that was perpetrated by Lehi and Irgun with the Haganah's connivance and the unfolding of Plan D, might perhaps have taken the leadership of the Yishuv by surprise. But they undoubtedly saw an opportunity to be exploited, a phenomenon to rejoice at -- Manachem Begin wrote in his memoirs, The Revolt, that 'out of evil, however, good came-and be encouraged. 'Doesn't he have anything more important to do?' was Ben-Gurion's reaction when told, during his visit to Haifa on 1 May 1948 that a local Jewish leader was trying to convince Arabs not to leave. 'Drive them out!' was Ben-Gurion's instruction to Yigal Allon, as recorded by Yitzak Rabin in a censored passage of his memoirs published in a censored passage of his memoirs published in 1979, with regard to the Arabs of Lydda after the city had been taken over on 11 July 1948....Plan D, however, was a major cause for the exodus, for it was strategically driven by the notion of creating Jewish contiguity even beyond the partition lines and, therefore by the desire to have a Jewish state with the smallest number of Arabs.
The debate about whether or not the mass exodus of Palestinians was the result of a Zionist design or the inevitable concomitant of war could not ignore the ideological constructs that motivated the Zionist enterprise. The philosophy of transfer was not a marginal, esoteric article....These ideological constructs provided a legitimate environment for commanders in the field to encourage the eviction of the local population even when no precise order to that effect was issued by the political leaders. As early as February 1948, that is before the mass exodus had started but after he witnessed how Arabs had fled West Jerusalem, Ben-Gurion could not hide his excitement."
from page 42:
"The reality on the ground was at times far simpler and more cruel than what Ben-Gurion was ready to acknowledge. It was that of an Arab community in a state of terror facing a ruthless Israeli army whose path to victory was paved not only by its exploits against the regular Arab armies, but also by the intimidation, at at times atrocities and massacres it perpetrated against the civilian Arab community. A panic-stricken Arab community was uprooted under the impact of massacres that would be carved into the Arabs' monument of grief and hatred."
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Nakba's Oral History Interviews:
http://www.palestineremembered.com/OralHistory/Interviews-Listing/Story1151.html____________
Israeli Haifa University historian Professor Ilan Pappe's lecture in Amsterdam in January 2007
--The Ethnic Cleansing of Palestine--
on Windows Media Mp3 (left click to listen online or right click and click on 'save target as') to download:
http://webdisk.planet.nl/houck006/publiek/album/Lectures/Broadband/Ilan%20Pappe%201.mp3Map showing the massive destruction of Palestinian towns after al-Nakba in 1948 - link:
http://www.palestineremembered.com/Acre/Maps/Story572.html