I had an interesting discussion about this with my grand-uncle last week. He was an RAF medic during WWII, joined up in 1937 and served in North Africa, Italy, Palestine, Germany before demobbing in '48. He is completely opposed to the idea, as a ex-serviceman, to deserters being pardoned.
Firstly, as a committed anti-Fascist, he believes Ireland should have entered the war - that the threat posed by Fascism had been made clear during the Spanish Civil War and nothing short of a comprehensive military defeat would ever stop 'those mad men'.
However, he also recognised that Dev made a pragmatic decision based on what he believed was best for Ireland. The country was financially in no position to wage war, was still suffering from the fall-out from both the War of Independence and the Civil War and would have had no option but to rely on British Forces at least initially. He fully believes that had British forces reappeared on Irish streets that civil war would have broken out again.
Interestingly, he did mention that the Irish army (his uncle was a captain) had a strong fascist element so he would have expected elements within the Irish army to ally with the fascists...
For him it is simply an issue that these men made an oath to serve in the Irish army and then broke that oath by deserting - what they did after that desertion is to him immaterial. The fact is they deserted.
He spoke of his experiences with deserters in the RAF and the effect this had on operations and moral, and the fact that as a serviceman one didn't have a 'choice' - one followed orders or the whole system collapsed.
He told me of an incident in '42 in North Africa when his C.O. issued an order for a particular airman to be sent on what was essentially a suicide mission. As Staff Sergeant my grand-Uncle requested that he be sent instead of this man, a conscripted father of four, but was refused permission. He had to order the airman on to the plane at gunpoint or face charges himself. I asked how he felt about this and he said he would have preferred to have gone in the man's place, but orders were orders and it was his duty as Staff Sergeant to ensure orders were followed and trust that those in charge, who could see the big picture, knew what they were doing.
He also spoke about discussions which took place among Irish servicemen in the British Forces as to what they would do were Ireland invaded -by either side. All were aware of the possibility and worried about what they would do.
It was a real concern but, he felt that if Britain invaded Ireland, he, as an Irishman, would have no choice but to desert from the RAF and fight for Ireland - but expected that had he ever been captured by British forces he would have expected to have been shot as a deserter.
As for the comments re: morality of fighting to prevent the Holocaust - he dismissed this out of hand. He said that although the powers that be may have had some knowledge of what was going on, the average serviceman had no idea and only became aware of it around '44/45 - by which point Ireland's involvement would have made no difference.
This is borne out by a conversation I had many years ago with a friend of my father's who was a GI. He was in a transport unit and was the driver of the first U.S. truck to enter a concentration camp - he said they had no idea what was in there - they knew it was some kind of prison, had absolutely no idea what they would find and not in a million years did they expect to see the horrors that were there.
My Grand-Uncle also spoke of how the Irish government and ordinary Irish people facilitated Irishmen and Irish women fighting for the Allies. He said that every time he came home on leave (in civvies of course) he was treated as a hero - even by his fanatically republican mother and sister (his father was unionist).
So, the upshot of the conversation was that he believes the deserters got off lightly, that had Ireland been invaded he would have felt compelled to return to fight but would have done so as a member of a Resistance movement not as a member of the Irish Army and would have fully expected to be shot for desertion if ever captured by the British.
That there was concern among Irish people that many in positions of authority in the Free State - in particular in the military and police- had fascist sympathies and could not be trusted so from a pragmatic point of view Dev took the right decision and that the Irish government is not given due credit for the aid it did give the Allies.