Final answer:
The U.S. Navy Department was established during the presidency of John Adams, in response to maritime geopolitical tensions in 1798.
Step-by-step explanation:
The U.S. Navy Department was established during the presidency of John Adams. Specifically, the Department of the Navy was created in 1798, as geopolitical tensions and the challenges of the burgeoning Napoleonic Wars in Europe necessitated a stronger naval presence. At the time, President Adams saw the need to protect U.S. interests at sea and bolster the country's defense capabilities.
Initially, the heads of the executive departments, like the Department of War, were appointed by President George Washington to serve as his advisors. It wasn't until Adams's presidency that the need for a separate Navy Department became clear, extending the scope of the U.S. military and providing a strategic advantage during the high seas conflicts of that era.