WI: United Ireland in WW2

  I think the big problem is that apart from the relatively small but influential Protestant minority in the south, especially around the Dublin Pale you have a very militant Protestant majority in the north.  Plus not only did they largely originate from Scotland - albeit several centuries before - there was still strong sectarian tensions in Scotland itself - an important factor in the old firm rivalry for instance.  They were bitterly opposed to coming under control of Dublin, hence the failure of all attempts to agree self government before the war as the Catholic 'Nationalists' insisted on this.  Then you have hard line extremist stage an attempted military coup in 1916 openly stating their friendship with Germany and after its rather clumsy suppression more hard liners win control of the bulk of the Irish seats in 1918 and starting basically a terrorist war.

  Under those circumstances I can't see any way that the northern Protestants would have been willing or could have been forced into such a union.  Even if either individuals or the government in London wouldn't have been willing to help them.  You would have seen much bloodier fighting and probably a more permanent 'solution' to the issue with forced movement of minorities both ways instead of just many loyalists leaving the south.

  Definitely de Velera was deeply anti-British.  I think that was more a factor than any actual liking of Hitler and if he had been executed after the coup attempt or better still died in the fighting, it might have helped ease things going forwards.  However the hard liners were still powerful even after the lost a civil war with the Dublin government that accepted the reality of partition so some such group may have gained power anyway. 

  There was no real chance for a unified Ireland after the 1916 East coup attempt as it caused too much concern in Britain and Ulster and the clumsy way it was handled helped cement the influence of the extremists in the south.  I have read some references that at times before 1914 the two sides got close to agreement on a deal by which the Protestants would have gotten enough guarantees to agree to such a union, which would still have been within the UK.  However this fell through and even if it had succeeded I suspect the hard liners would have sought to undermine it, especially on the 'Catholic' side.  However it could have saved a hell of a lot of suffering in Ireland and also made Britain markedly stronger in WWII with access to southern Irish bases.