Final answer:
King George III declared the colonies to be in rebellion in response to the Olive Branch Petition.
Step-by-step explanation:
King George III reacted to the Olive Branch Petition sent by the Second Continental Congress by declaring the colonies to be in rebellion. The Olive Branch Petition was an attempt by the colonists to restore harmony with Britain by appealing to the king to address their grievances. However, instead of considering it carefully and agreeing with it, King George III rejected the petition and saw it as an act of defiance, leading to further escalation of tensions between Britain and the colonies.
Learn more about King George III's reaction to the Olive Branch Petition