I must say I have never seen such a collection of urban legends attributed to Americans' collective memory of history.

This view must have to do with the radical left of the liberal-progessive wing of intellectuals living in campus ivory towers.

Most Americans are not sure if the Civil War came before or after WWI. The French gave us deep fried foods (mostly potatoes) and very high priced wine.

The U.S. shift to French army regulations has no mysterious basis. It has to do with the political struggle between the Federalists and the "Anti-Federalists" (Republicans), and the election of 1800. Adams represented the Anglophiles and Jefferson represented the Anglophobes. Adams was discredited by the Jay Treaty.

Two passionate Republicans - Benjamin Franklin Bache and William Duane - published a notorious newspaper, the "Aurora". Since they had a printing press, they printed other things also. One of those things was a translation of the French "Regulations" for distribution to Republican militia companies which were formed to counter-balance the Federalist militia companies. Remember that at this time the War Department of the National Government had only the most tenuous control over the militia of the states. When Jefferson became President, his War Department naturally preferred the Republican militia companies' important officers. They knew the Aurora / Duane regulations; so that version was propagated.

Who knows if it had to do more with Francophilia or Anglophobia? There was a very large German speaking population, but that did not seem to make Prussian (or other German language regulations) popular at all.

Once something gets started in the military, it is hard to stamp out and start over.