Hazelwood played a major role in the American effort in keeping British ships from reaching Philadelphia by way of the Delaware River.
In the months leading up to the British siege of Fort Mifflin Washington's headquarters at this time was located north of Philadelphia in Whitemarsh where he maintained frequent communication with Hazelwood, sending him reports, orders and advice.
Fort Mifflin, commanded by Lieutenant Colonel Samuel Smith, was located on an island in the middle of this river and was a key point of defense for the Americans.
The fortress, along with Fort Mercer on the east bank, were the only obstacles preventing the British naval access to Philadelphia.

Vice Admiral Howe dispatched a message to Hazelwood requesting that he surrender the Pennsylvania fleet, allowing Howe and his fleet to control the Delaware Bay, where Hazelwood was allegedly promised a pardon from the King if he cooperated.
Hazelwood refused the dubious offer, declaring that he would "defend the fleet to the last".

The successful siege upon the stone and earthen fort required the prolonged bombardment by the British Navy under the command of Admiral Howe, also involving land batteries, lasting from September 26 to November 16, 1777.
The standoff and defense of the fort allowed time for Washington and the Continental Army to safely deploy for the Battle of White Marsh and its subsequent withdrawal to Valley Forge.
Washington received warnings from Generals Porter and Lee, stationed on the Schuylkill River at Philadelphia, that the British were making communication runs across the river at night using small boats.
In a letter of November 4, Washington advised Hazelwood to do all he could to stop the activity.
Hazelwood's efforts to end the communications were less than effectual.
Several days before the fall of the fort Washington dispatched another letter to Hazelwood inquiring about his status, urging that if at all possible to remain at his station with the fleet after the fort has fallen so as to hinder and prolong British operations long enough to allow the river to freeze over, preventing passage of supply ships into Philadelphia until the spring thaw.

After weeks of almost constant bombardment from British ships and batteries and receiving extensive damage and heavy casualties, Fort Mifflin was finally abandoned on November 15, while the fort's flag was left there and remained flying.
Capture of the fort was finally effected on November 16, leaving only Fort Mercer on the Red Bank of New Jersey to defend the river.
Two days later, with 7,000 British troops led by General Cornwallis and with General Howe's 1000 troops marching north to Fort Mercer, Hazelwood scuttled many of the smaller ships and galleys located there while Captain Christopher Greene and the American garrison abandoned the fort on November 20 leaving it to the advancing British.
Two days later General Washington called a Council of War, meeting with several of his generals on board one of Hazelwood's ships.
During the assembly Washington's council recommended that Commodore Hazelwood lead the effort "with the first favorable wind", and get the American ships and supplies in the area safely up river just past Burlington, New Jersey.
On the night of the 21st Hazelwood and the American naval fleet managed to pass by the British who were busy securing their position in Philadelphia, with no shots fired by them to stop passage of Hazelwood and the American fleet.

Soon after the fall of Forts Mifflin and Mercer Washington and other commanders sought an explanation about what lead to their capture.
 Washington had sent General Varnum to Fort Mifflin in November to quell the frequent command disputes between garrison and naval commanders with little success.
Varnum faulted himself and offered his apologies to Washington.
Hazelwood and Smith, already rivals, laid the blame on each other.
Exchanges between the two became increasingly heated and bitter, while each embarked on campaigns in Congress and the Pennsylvania Council for the purpose of exonerating themselves of any sh
Hazelwood played a major role in the American effort in keeping British ships from reaching Philadelphia by way of the Delaware River. In the months leading up to the British siege of Fort Mifflin Washington's headquarters at this time was located north of Philadelphia in Whitemarsh where he maintained frequent communication with Hazelwood, sending him reports, orders and advice. Fort Mifflin, commanded by Lieutenant Colonel Samuel Smith, was located on an island in the middle of this river and was a key point of defense for the Americans. The fortress, along with Fort Mercer on the east bank, were the only obstacles preventing the British naval access to Philadelphia. 
Vice Admiral Howe dispatched a message to Hazelwood requesting that he surrender the Pennsylvania fleet, allowing Howe and his fleet to control the Delaware Bay, where Hazelwood was allegedly promised a pardon from the King if he cooperated. Hazelwood refused the dubious offer, declaring that he would "defend the fleet to the last". 
The successful siege upon the stone and earthen fort required the prolonged bombardment by the British Navy under the command of Admiral Howe, also involving land batteries, lasting from September 26 to November 16, 1777. The standoff and defense of the fort allowed time for Washington and the Continental Army to safely deploy for the Battle of White Marsh and its subsequent withdrawal to Valley Forge. Washington received warnings from Generals Porter and Lee, stationed on the Schuylkill River at Philadelphia, that the British were making communication runs across the river at night using small boats. In a letter of November 4, Washington advised Hazelwood to do all he could to stop the activity. Hazelwood's efforts to end the communications were less than effectual. Several days before the fall of the fort Washington dispatched another letter to Hazelwood inquiring about his status, urging that if at all possible to remain at his station with the fleet after the fort has fallen so as to hinder and prolong British operations long enough to allow the river to freeze over, preventing passage of supply ships into Philadelphia until the spring thaw.
After weeks of almost constant bombardment from British ships and batteries and receiving extensive damage and heavy casualties, Fort Mifflin was finally abandoned on November 15, while the fort's flag was left there and remained flying. Capture of the fort was finally effected on November 16, leaving only Fort Mercer on the Red Bank of New Jersey to defend the river. Two days later, with 7,000 British troops led by General Cornwallis and with General Howe's 1000 troops marching north to Fort Mercer, Hazelwood scuttled many of the smaller ships and galleys located there while Captain Christopher Greene and the American garrison abandoned the fort on November 20 leaving it to the advancing British. Two days later General Washington called a Council of War, meeting with several of his generals on board one of Hazelwood's ships. During the assembly Washington's council recommended that Commodore Hazelwood lead the effort "with the first favorable wind", and get the American ships and supplies in the area safely up river just past Burlington, New Jersey. On the night of the 21st Hazelwood and the American naval fleet managed to pass by the British who were busy securing their position in Philadelphia, with no shots fired by them to stop passage of Hazelwood and the American fleet.
Soon after the fall of Forts Mifflin and Mercer Washington and other commanders sought an explanation about what lead to their capture.  Washington had sent General Varnum to Fort Mifflin in November to quell the frequent command disputes between garrison and naval commanders with little success. Varnum faulted himself and offered his apologies to Washington. Hazelwood and Smith, already rivals, laid the blame on each other. Exchanges between the two became increasingly heated and bitter, while each embarked on campaigns in Congress and the Pennsylvania Council for the purpose of exonerating themselves of any sh
John Hazelwood