Here is what I did not know that morning, as I drove myself to my own graduation with my jaw set against the loneliness of it.

I did not know that for the previous three weeks, in the hours when I was at school or asleep, my grandmother had been writing a letter.

Not a short note — a letter, a real one, twelve pages long, in her shaky and still-elegant hand, a hand that could now only write for a few minutes before it had to rest.

I did not know that the letter was addressed to a commanding officer I had never met, on a base I could not have found on a map.