Polis Ranger

From the book What This Cruel War Was Over by Chandra Manning:

During the Civil War, most Union soldiers didn’t care about the issue of slavery and were more focused on preventing the collapse of the United States. This would change as many Union soldiers encountered horrific circumstances of slavery and it’s widespread influence on southern society, with accounts like these: “Pvt. Chauncey Cooke experienced an epiphany when a fair-skinned slave woman whose children had been fathered and sold by her master told the young Wisconsin boy that her children looked like him, and that she missed them dreadfully because she loved them “just likes you mammy loves you.” ” “When an Iowan encountered a young child about to be sold by her own father, who was also her master, he vowed, “By G–d I’ll fight till hell freezes over and then I’ll cut the ice and fight on.”Sgt. Cyrus Boyd.

The president called in the US Marines and the state militia (in addition to the US Marshalls who arrested him and held him in jail) to allow this one man to be dragged back to slavery.

There’s more, which you can see on Burn’s Wikipedia and on the Committee of Vigilance’s page, the abolitionist group founded after the Fugitive Slave Act to protect and aid Boston’s large community of escaped slaves & black citizen.