H. Irving Hancock (1916) Conquest of the United States – a series comprising four books:
- The Invasion of the United States, or Uncle Sam’s Boys at the Capture of Boston
- In the Battle for New York, or Uncle Sam’s Boys in the Desperate Struggle for the Metropolis
- At the Defense of Pittsburgh, or The Struggle to Save America’s “Fighting Steel” Supply
- Making the Stand for Old Glory, or Uncle Sam’s Boys in the Last Frantic Drive
All set around 1920 and depicting the Invasion of the USA by a Germany which has already won the Great War in Europe. [more at: http://www.sf-encyclopedia.com/entry/hancock_h_irving]
Full text at:
The Invasion of the United States – http://babel.hathitrust.org/cgi/pt?id=hvd.hn1qqk;view=thumb;seq=1
At the Defense of Pittsburgh – https://archive.org/details/atdefenseofpitts00hanc