to begin to fight; to attack or commence someone or something. The two boys set to almost as soon as they met each other. They set to and fought for about ten minutes, cursing and screaming.
1. Apply oneself, begin, work energetically, as in We set to revamping our policy on child care, or She set to studying for the bar exam. [Early 1400s]
2. Begin fighting, as in Both of them were furious, and they set to immediately. [First half of 1700s]