Why does the headless horsemen chase Ichabod Crane in "The Legend of Sleepy Hollow" ?

The headless
horseman appears as a specter who haunts the scene where Major Andr© was killed and he chases
Ichabod Crane.

In "," the headless horseman confronts Ichabod Crane
on his way home from the Van Tassel's party by the side of a bridge. He rides at the same pace
as Crane as though he desires a race with him, a race similar to what Brom Bones has claimed to
have had with this ghost. When the light sets the horseman into relief against the sky, a
horrified Ichabod observes that this ghost is headless. As the frightened Ichabod realizes that
the head is carried by the rider on the pommel of his saddle, Crane "rained a shower of
kicks and blows upon old Gunpowder" and fearfully hurries toward home, but the specter's
dark horse keeps pace with him.

When the two horses reach the road turning
off to Sleepy Hollow, Gunpowder, who seems "possessed with a demon," plunges headlong
down a hill to the left. The road that the old horse goes on leads to the famous bridge of the
ghost story. Somehow, though, the girth of the saddle loosens, and Ichabod has to grab the
horse's mane as the saddle falls off. An opening in the trees gives Ichabod hope as he perceives
that the church bridge is near. "If I can but reach the bridge, I am safe," thinks
Ichabod. Old Gunpowder is given a hard kick in the ribs, and he jumps upon the resounding planks
of the bridge. When Crane turns to look behind him, he sees the goblin standing in the stirrups
of his saddle as he hurls his head at the frightened schoolmaster. This "horrible
missile" hits Crane, sending him headlong into the dirt as Gunpowder and the black steed
speed past him.

The next day the old horse is discovered without his saddle,
quietly grazing at his master's gate. His saddle is gone, and the reins are under his feet. The
children have come to school, but there is no schoolmaster to be found. When a search is
conducted, only the hat of Ichabod Crane is found by the stream near the bridge; close beside
this hat is a smashed pumpkin. Later on after the people of the town research the stories of the
Galloping Hessian, they conclude that Ichabod has been carried off by this villainous
specter.