[ansel12]

Does he have a time machine so he can go back and encourage at least one of his five boys to serve his country in the military?

Even at this date any one (or all) of those five boys can still enlist.

[Waryone]

If he did that now, it would not help him. It would just seem like another disingenuous move on his part. But if they had been encouraged from birth to love and want to serve their country, we would have seen it by now.