These thrall units are extremely weak but can serve as the first line of defense against a variety of enemy unit types.
The Rise of the Witch-king tells the story of the evil Witch-king’s rise to power, domination of Angmar and invasion of the great kingdom of Arnor. After the Great Plague in 1636 which devastates Gondor and desolates many parts of Eriador, the southern part of Arnor, the Witch-king finally destroys Fornost, and takes it as his own fortress. The tower of Amon Sûl is destroyed, but the great fortress of Fornost is defended, and war continues. The Witch-king settled in Angmar, and after having built an army there, invades Arnor in the year 1409, and waged a 500-year war against the kingdom of Arnor, the north-kingdom of Men. In the year 1300 of the Third Age, evil things started to stir in Middle-Earth again, and the Nazgul re-appeared. After a thousand years of peace that followed the War of the Last Alliance, evil once more began to spread across Middle-earth.