June 18th, 1942.
Y'know, he's very close to Ennis and Jack's age. In my worldview, I haven't exactly figured out what year they were born. If it is 1943, then they both turned 20 in 1963, but they were 19 while they were up on the mountain.
That means both of their birthdays would be in the fall. However, in my story (1976), Jack mentions a couple of times that they are both 33, which means they would have had their birthdays already. Hmm, a detail I probably should have worked out. Oh well, too late now.
Leslie