This quote was relayed by Cumann na mBan member Brigid Lyons Thornton in the 1970s documentary Curious Journey about her time spent in prison immediately following the 1916 Easter Rising:
Early that morning then I heard a terrible volley of shooting and I asked the one who came to me, a Miss McInnerney, I said ‘What was all the shooting this morning?’ And she said, ‘They were shooting some of the men.’ Now I didn’t know who or what and I didn’t believe it. Later that day we were let out for about ten minutes’ exercise and we met a lot of other girls who had been at other centres during the week and I said to one of them. ‘I heard they were shooting the men.’ And she said, ‘Don’t you worry, they’re not going to shoot any of the men. They’d be too much afraid of America.’
Well the next morning the shooting was on again and again and again, every morning after that at about five o’clock. I could hear the men marching out down by my cell door, a heavy march and then out and then the volleys.
Why would the British government fear some kind of response from the United States for executing what, from the Downing Street perspective, were unlawful rebels? Would the British have feared a U.S. government diplomatic response specifically or more a negative response from the American (and Canadian?) public? And more importantly, was an American response even a consideration at all for the government? If so it didn't stop them from executing 16 men. So why would Irish republicans believe that the British government would care?
Thank you!
Shortly after the executions, when de Valera had his death sentence reprieved, the story was that his American citizenship by birth was the saving factor for why he was saved, and others were not. It's interesting to note that this was not Dev's personal belief, he wrote in 1969 "The fact that I was born in America would not have saved me" and "I have not the slightest doubt that my reprieve in 1916 was due to the fact that my court-martial and sentence came late"
Complicating the issue is that the US consuls in Ireland at the time did perform consular services for US citizens arrested in the rising, and that one did indeed write to the British noting that Dev had US citizenship (but not asking for any particular outcome). It seems, though, that the US citizenship was not a major factor in the commutation.
Dev was not the only rebel not to be executed, he shared that distinction with Thomas Ashe. Both were tried later than the others, the public backlash from the earlier executions having had time to affect their own destiny and causing the British to change their minds on the matter. Dev simply wasn't considered important enough to shoot.
However, it certainly played well in the US. The Boston American was happy enough to announce that "Citizenship in US Saved Valera's Life" (complete with typo on Dev's name). From the American perspective, the Irish were trying to do for themselves what the US had managed a century prior, and there was no small Irish-American vote in Woodrow Wilson's constituency, Wilson himself being a declared supporter of Irish Home Rule. However, it's interesting to note the difference between what people thought the Americans might do or think vs what they actually did after the fact.
This paper from a University of Limerick professor goes into the details of the US reaction to the Easter Rising. Two items come to the front. One is that Wilson observed "the great shock opinion in this country has received from the course of the British government towards some of the rebels," which is true enough. The executions didn't go over massively well (though putting down the rising was less controversial)
The other, though, is that the primary practical American concern wasn't so much whether or not the Americans approved of the British handling of the rebellion on moral grounds as much as the practical effect that having an uprising in Ireland would have on the British prosecution of the war against Germany. The Americans felt that the British couldn't afford the distraction and that executing the rebels was liable to increase anti-British sentiment, cause more trouble and was a mistake on those grounds. Although certain Congressmen with heavy Irish-American constituencies certainly made a lot of noises, Wilson actually remained generally quiet on the subject. In the elections later that year, Wilson himself thought his lack of action on the matter would cost him the Irish-American vote, but in the final analysis, they still generally voted for him anyway simply because for the domestic issues which were more important to the voter as Americans (who just happened to be of Irish descent), he was better than the opposition.
For equally obvious reasons, the British had a concern towards not deterring the US from joining in the War on the British side. In one of those quirks of fate the Commander in Chief sent to quell the uprising, a Lt Gen Sir John Maxwell was father-in-law to the aide of "Colonel" Edward House, one of Wilson's closest advisors, and he was well sensitive to the military implications of US participation. Of course, these are the sorts of things that the average person on the street of Dublin would have no idea, but it's still interesting to consider the various permutations of ramifications. The simplistic position of "UK wants US in the war on its side and doesn't want to annoy the US and there are lots of Irish in America" is a view which average folks could understand and hold prior to the rebellion.
Dev himself was quite happy to milk the US connection after the fact. When he toured the US afterwards, he was touted as a 'son of America trying to spread liberty', and even when he hosted JFK in Dublin, in 1963, he told JFK specifically his US citizenship saved him. All's fair in love, war and politics.