I understand that the United Arab Republic was a move by Syrian Ba'athists to have Nasser remove the communists from Syria's government. Did Nasser believe that the UAR would be forever, or did he sense that it was fragile? What about the Syrian leaders? What about the Egyptian and Syrian people? Was there a widespread belief that the UAR would grow to incorporate all Arab peoples, or was this ambition considered unrealistic?
Nasser although Pan-Arabist, was extremely aware of how his own country was in such a fragile state, and did not want to take an active policy in creating a Pan-Arab state, until Egypt was better off. The union with Syria was an opportunity that presented itself, and not one Nasser was actively setting up. That being said just because he wasn't originally keen on setting up a pan-arab state in his position, he did see the acquisition of Syria as beneficial.
The union broke apart because of Egyptian dominance in 'Syrian' local government. Depending on what view you take this dominance either came from Nasser purposeful instillation of Egyptian in positions of power, or as just a natural occurrence that presented itself when two countries with disproportionate population merged. Egypt's larger population, larger military, and larger dominance in general in the Arab world led them to become dominant.
The common sentiment was that it would be a long lasting union, and people still have wishes it continued.
As mentioned the Syrian leaders were greatly upset with the union after occurring.
There were plans for more countries to join the union, however may have been a slightly unrealistic ambition.
Most information taken from Cleveland. A modern history of the middle east.
as a follow up: can anyone comment on how close Iraq was to joining this union? There was a coup there in '58 and the nominal leader: Quasim, I thought wanted to join the Pan Arab league. There were dissenting forces underneath him and he was assassinated in '63. Then Arim died in helicopter crash in '66 which I guess the Baathists moved into this vaccum.
So I guess there was a lot of unrest there when the Baathist party emerged, but didnt some elements in Iraq want to join the union?