"The herd of possessed swine"
by cm

In Mark 5, Jesus expels a "legion" of demons from a deeply troubled individual:

A large herd of pigs was feeding on the nearby hillside. The demons begged Jesus, "Send us among the pigs; allow us to go into them." He gave them permission, and the evil spirits came out and went into the pigs. The herd, about two thousand in number, rushed down the steep bank into the lake and were drowned. 

Mark 5, 11-13

The same biblical passage is referred to by Holden Caulfield in The Catcher in the Rye, although in a rather different tone.