Answer:
Flails are used for threshing grain, a process that involves beating the grain as it sits on stalks. The flail consisted of two pieces of wood, the longer about thirty inches, or perhaps 75 centimeters, in length, and the other shorter by the width of a hand or more. They were joined by a short bit of chain, so the one not held could pivot in the beating process.
They were also used in wars, as were a number or agricultural tools. The earliest recorded use of them was about the years 1420 to 1425.