"Mama, Look Sharp" is one of the most gut-wrenching songs ever performed on Broadway.
Them soldiers, they fired. Oh ma, did we run
But then we turned round and the battle begun
Then I went under, oh ma, am I done?
Hey, hey, momma look sharp...
Adams' realization that he'll have to allow slavery in America to avoid a civil war. And in real life, he (or rather, his cousin Sam) actually did predict that one was inevitable within a hundred years, which wasn't included in the play because people wouldn't believe it.
A more minor one in "Yours, Yours, Yours." Adams, seeing Jefferson with Martha, is reminded of how far he is from Abigail, and he's clearly trying to stave off the loneliness when he invites Franklin to dinner and is rebuffed because Franklin has a date. Then he goes into "Yours, Yours, Yours" with Abby where they both lament their separation from each other with such lines as "I've forgotten the feel of your hand." It's made more poignant by the fact that the most sentimental lines were lifted directly from John and Abigail's real letters to each other. More restrained they may be in expression, but there's no doubt how much they love each other.