Immediately after landing at Pevensey, William ordered the construction of a motte-and-bailey castle within the walls of the old Roman fort of Anderida. The speed of this construction -- completed within days -- demonstrated the Norman priority of securing a defensible base before advancing inland. The castle guaranteed William a fallback position if the campaign went wrong and served as the initial headquarters of the invasion. It was the first of hundreds of Norman castles to be built in England.
The size of the opposing forces is not recorded in the surviving sources.
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