The Musket Boys series.
As the titles imply, this Stratemeyer Syndicate series is set during the American Revolutionary War. Edward Stratemeyer had written other stories on his own during the Colonial period but this was produced through the Syndicate with Weldon J. Cobb writing from his outlines.
The books were very expensive in the original Cupples & Leon editions, retailing for $1.00. This helps to account for the difficulty in finding them today. There are cheap Goldsmith reprints for the dime store market and they are much easier to find. I think these reprints are from about 1930 but could be somewhat earlier considering when Cupples & Leon gave up on the series (as they did several others of this period).
1. Musket Boys of Old Boston (1909)
2. Musket Boys Under Washington (1909)
3. Musket Boys on the Delaware (1910)
4. Musket Boys at Princeton (phantom)
Only three volumes were written and published. The fourth title was advertised as a next title at the end of volume 3. It is a “phantom title.”
The pen name created for this series, and used for another, was intended to evoke George Washington and General Warren of Bunker Hill fame.