King Vortigern the usurper sat upon his throne in London, when, suddenly, upon a certain day, ran in a breathless messenger, and cried aloud—
"Arise, Lord King, for the enemy is come; even Ambrosius and Uther, upon whose throne thou sittest—and full twenty thousand with them—and they have sworn by a great oath, Lord, to slay thee, ere this year be done; and even now they march towards thee as the north wind of winter for bitterness and haste."
At those words Vortigern's face grew white as ashes, and, rising in confusion and disorder, he sent for all the best artificers and craftsmen and mechanics, and commanded them vehemently to go and build him straightway in the furthest west of his lands a great and strong castle, where he might fly for refuge and escape the vengeance of his master's sons—"and, moreover," cried he, "let the work be done within a hundred days from now, or I will surely spare no life amongst you all."