De Valera grew up in Ireland, fought in Ireland, spent time in jails for his efforts towards Irish independence, and spent 27 years as head of the Irish state. In the wake of that, to say that his citizenship was American (and thereby attempt to imply that he's *not* really Irish) is a complete distortion of the truth to support your position. This is the same tactic you (rightfully) accuse the Bush administration of constantly using.
Further, the claim that de Valera invoked his American birth to save his own life has come only from you - I find no reference to this on the half-dozen or so sites that have his biography. In each case, they mention that his birth nation was a factor in his non-execution, but none mentions that he was the one who claimed it. In fact, the only quote from 1916 I *did* find from him was "shoot me if you will, but arrange for my men". Hardly sounds like the self-serving coward you describe.
Your continual insistence on 'a number' of men who served in WWII prior to Pearl Harbor makes it clear that you have no real allegiance to the truth - you merely want to tally up points on some scoreboard in your head.
Regardless of the presence or lack of 'a number' of US volunteers, the facts are clear; during the years 1939-1941, the US gave billions in aid that was never repaid, and there were volunteer pilots flying in the Chinese and European theaters.
Do you dispute those facts? It's a simple yes/no question. If you answer 'yes', then you make it obvious that you're completely ignorant. If you answer 'no', then your insistence on a number of volunteers is pointless and irrelevant.
Either way, you've got no legs to stand on. Give it up.