The 日 jump
The horse moves one point straight then one point diagonally — the shape of the character 日. Unlike the chess knight it cannot leap over anything: if the point beside it in the straight direction is occupied, that leg is hobbled (蹩马腿) and the whole jump is illegal. Count legs before you count destinations — here the pawn on a1 hobbles the jump to b2, while the jump to c1 walks over the empty b0. From forks to the horse-cannon mate, half of all horse tactics begin by hobbling or freeing a leg.
Solve the challenge to finish this lesson.