We all know that the epic DoD starts with President Jefferson dying of a heart attack in 1809. But WI he died in 1789 no more than six months after the inauguration of President Washington?
This would have a huge impact on Hamilton and the Federalists, as his arch-nemesis would be gone before they even started arguing over the National Debt etc. The Democratic-Republicans (or similar) would have to form under someone else. Then, he won't be around to wrangle with the National Bank, the location of the Capital, the Alien & Sedition Acts, the Vice Presidency, the acrimonious Election of 1800, the Embargo Act..... and so on ad nauseum.
Obviously there are plenty of people to fill in his shoes, like James Madison to name just one, but how much impact would his total absence make in the first 20 years of Constitutional US government?