George Washington took two Oaths of Office.
One was to The United States of America on April 6, 1789. That is the political office owed to the land jurisdiction States and the American people holding the non-delegated powers.
The other Oath of Office taken on April 30, 1789 was to the Federal United States and its new Constitution as President of the United States. That is the business office of the top executive of the Federal Government exercising the delegated powers.
One Supreme Office on the land and one on the sea.
The President was supposed to stand with one foot on the land and one in the sea, able to provide for the orderly administration and functioning of both jurisdictions to best serve the general welfare and benefit of the people and the country as a whole.
The order of the Oath-taking proves beyond any doubt that the Supreme Office was the political Office of the President of The United States of America, which had to be entered and bonded and commissioned and affirmed under Oath before the subject jurisdiction of the delegated powers could be similarly entered into.
You have to have a country before you can delegate powers to operate in the international jurisdiction of the sea.
And that is why Washington took two Oaths and why the Oath to The United States of America had to come first.