Final answer:
King Alfred was worried because a fierce group of people had come across the sea to fight him.
Step-by-step explanation:
King Alfred was worried because a fierce group of people had come across the sea to fight him. The selection does not specify the exact reason why they came, but it can be inferred that they posed a threat to King Alfred and his kingdom. Their strength and ability to travel by sea made them a formidable opponent, causing King Alfred to be concerned about the safety and security of his kingdom.
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