Final answer:
The defeat of the Federalists in the election of 1800 was primarily due to a combination of factors, including internal divisions and unpopular policies. John Adams' decisions and Alexander Hamilton's criticism contributed to the downfall of the Federalists.
Step-by-step explanation:
The defeat of the Federalists in the election of 1800 was primarily due to a combination of factors including the party's internal divisions and policies that had alienated both Federalists and Republicans. John Adams' decision to settle with France and pardon those involved in Fries's Rebellion was disliked by his own party. The opposition party, on the other hand, disliked the emergence of a standing army and the passage of the Alien and Sedition Acts. Additionally, Alexander Hamilton, a prominent Federalist, played a role in opposing Adams by suggesting that he did not have the necessary talent for administration.