The Pennsylvania State Navy was formed on July 6, 1775 by the Pennsylvania Committee of Safety for the defense and safety of Philadelphia's waterborne approach - the Delaware.  Thirteen row galley's were ordered built, each to be armed with a single large cannon in the bow.  Amazingly, the first of these was launched on July 19th, and by August there were six.  Completed and commissioned, they were named:

The armament ranged from 18-pounders up to 32-pounders.  By the close of 1775, ten fire rafts were built.  In 1776 two floating batteries, the  ARNOLD  and  PUTNAM,  were commissioned and crewed by Pennsylvania State Marines.  By August of 1776, the Pennsylvania State Navy totaled twenty-seven vessels crewed by 768 men.¹  Toward the end of 1776, twenty-one smaller vessels were ordered built.  They were called "armed boats" or "guard boats", and each were armed with 2-pounder, 3-pounder or 4-pounder cannon in the bow.  They were named:

The Navy saw action for the first time on May 6, 1776 when it engaged the British ships ROEBUCK 44 and LIVERPOOL 28.  After a brief engagement, both enemy ships were forced to withdraw south past Newcastle, Delaware.

On September 26, 1777, British General Sir William Howe took possession of Philadelphia.  Keeping him from receiving the needed supplies were the Pennsylvania State Navy, Fort Mifflin, Fort Mercer and other fortified posts along the Delaware River south of the city.  The Royal Navy was intent on forcing its way north up the Delaware to relieve the troops in Philadelphia, and to do so meant fighting their way clear of river obstructions and the State Navy vessles.

On October 23, 1777, the British ship AUGUSTA 64 ran aground midchannel off Fort Mifflin.  Concentrated fire from the State Navy boats and from Fort Mifflin set fire to the ship, and the AUGUSTA exploded.  The British ship MERLIN 18 also ran aground and was set on fire by its crew to avoid capture.

After the fall of both Forts Mifflin and Mercer, some vessels from the State Navy made their way north past Philadelphia where they were scuttled to avoid capture.   Larger State ships were set on fire by their crew to keep them from falling into British hands.

Detailed accounts can be found in the following text:

"The Pennsylvania State Navy, 1775-1781.  The Defense of the Delaware" by John W. Jackson, Rutgers University Press, 1974.

⁽¹⁾ "Ships and Seamen of the American Revolution" by Jack Coggins, Promontory Press, 1969.

Although both are out of print, they can regularly be found at www.abebooks.com.