"But, mother, I won't be alone. Other children will go with me, And march the streets of Birmingham To make our country free."
The child is speaking again. She knows that other children attend the marches—which gives us a sense of the solidarity behind these marches. As well, she believes being in this company will make her more safe.
So, why does she want to march? "To make [her] country free," she says. And she was right: the marches in Birmingham were instrumental to the Civil Rights Act of 1964. One last thing before we go: who is this girl? We don't have a name or much else to go by, and we're nearly halfway done with the poem.
Her anonymity is no accident, though. Randall is giving a voice to a child that can represent many children; we aren't given too many specifics, or even her name, for this reason.