Wikipedia
Whitecapping is a violent lawless movement among farmers that occurred specifically in the United States during the late 19th and early 20th centuries. It was originally a ritualized form of enforcing community standards, appropriate behavior and traditional rights. However, as it spread throughout the poorest areas of the rural South it took on a distinct anti-black characteristic.
Usage examples of "whitecapping".
The rapid current frothed and boiled over underwater rocks, whitecapping the surface and occasionally sending up a spray of diamond drops.
Winds drove squawls across the vast silver belly of Wat-tala Bay, whitecapping the water, sending storm chop to tear at the beach.
Not so far above him, Elbryan could see the snow on this mountain and on all the others, a whitecapping that the young man suspected might be perpetual.