Final answer:
The inception of the U.S. Navy included ships-of-the-line, frigates, and sloops-of-war, with each class serving different roles in Naval warfare and contributing to the early strength and strategy of the Navy.
Step-by-step explanation:
The three classes of Naval vessels that existed at the inception of the United States Navy were ships-of-the-line, frigates, and sloops-of-war. Ships-of-the-line were heavy warships with multiple gun decks and were the largest and most formidable at the time, often carrying sixty-four or more guns. Frigates were designed for speed and maneuverability with a single gun deck, and sloops-of-war were smaller still, but they were also warships, albeit with fewer guns and more versatility in their roles. These vessels represented the backbone of early Naval power and played crucial roles in the development of naval tactics and maritime dominance.