I have always thought of how tiring and difficult it must have been for R. E. Lee to have had to worry about his crippled wife during the war. I know she had RA, and I have often assumed that she would be diagnosed with something like Lupus of Fibromyalgia today. He must hast been very concerned for he health at all times.
They had a whole herd of children, so it's obvious that she wasn't always in such ill health. I know from reading is letters that she did everything within her power to contribute to the war effort all the way until the end, by way of knitting socks and sending baskets of whatever she could find that was edible to his HQ, which he promptly gave away to hungry men.
The phrase "Behind every good man, there is a great woman." comes to mind when I picture her.