Final answer:
The beginning of a stronger, more assertive presidency began with George Washington's inauguration as the first President of the United States.
Step-by-step explanation:
The beginning of a stronger, more assertive presidency can be traced back to George Washington when he took office as the first President of the United States. In his inaugural address, Washington emphasized the importance of preserving liberty and placed the power in the hands of the people. This marked the beginning of the growth of both the formal and informal powers of the presidency.