1918: The Allies and the Central Powers sign the Treaty of Versailles ending WW-I. Germany takes all the blame for the start of the war and is given impossible sanctions.
1930: The Great Depression begins with the crash of the stock market. Germany who was barely holding on is ravaged and the German Republic fractures back into the original German nations right before the unification. Prussia takes advantage of the situation and reunifies the German states under the Prussian banner. France officially condones the action but does nothing.
1933: President FDR is elected to the presidency of the USA. USSR spies in the US destroy the George Washington Bridge. New York blames New Jersey civilians for the destruction and demands New York state troopers be allowed jurisdiction. New Jersey refuses.
1934: FDR's anti-constitutional policies come to a climax with the American Revitalization Act which gives the government the right to forcibly change people's jobs or housing. As a result a conference is held in most states regarding its constitutionality. Nearly all agree it's unconstitutional and secede. (The states who secede are all but Maryland, Virginia, Pennsylvania and New York).
US troops in the seceding states join the fledgling nations.
1935: FDR is granted emergency powers. He sends troops to recapture New England. They're soundly defeated at the Battle of Boston where the militia units over run the US troops. US forces heading south are killed by insurgents and rarely engage any units in a traditional form. The New England States unite into the Republic of New England, only Rhode Island doesn't accept the invitation and becomes the Republic of Rhode Island and the Providence Plantations. All of the other states fail to join one another.
1936: After nearly no victories the US admitted defeat and recognize the states independence.