Final answer:
Johnny D calms down the other inmates by singing freedom songs, which serve as a way to unite and soothe the spirits of those incarcerated.
Step-by-step explanation:
In response to the question of how Johnny D calms down the other inmates, it should be noted that while the specific character of Johnny D is not provided in detail within the context, we can refer to historical scenarios for context. Drawing from the information given, it appears that when jails became overcrowded, individuals were sent to local fairgrounds where they comforted each other during their time until release.
One of the ways they did this was by singing freedom songs. These songs served not only as a form of protest but also as a means to unite and soothe the spirits of those incarcerated. Spirituals, often deeply-rooted in African American history for their role during the era of slavery and the civil rights movement, were commonly sung to maintain hope and solidarity.