Washington, writing to his brother John Augustine, says: "If it had not been for a thick fog, which rendered it so dark at times that we were not able to distinguish friend from foe at the distance of thirty yards, we should, I believe, have made a decisive and glorious day of it. But Providence designed it otherwise, for, after we had driven the enemy a mile or two, after they were in the utmost confusion and flying before us in most places, after we were upon the point, as it appeared to everybody, of grasping a complete victory, our own troops took fright and fled with precipitation and disorder. How to account for this I know not, unless, as I before observed, the fog represented their own friends to them for a reinforcement of the enemy, as we attacked in different quarters at the same time, and were about closing the wings of our army when this happened. One thing, indeed, contributed not a little to our misfortune, and that was a want of ammunition on the right wing, which began the engagement, and in the course of two hours and forty minutes, which time it lasted, had, many of them, expended the forty rounds that they took into the field. After the engagement we removed to a place about twenty miles from the enemy to collect our forces together, to take care of our wounded, get furnished with necessaries again, and be in a better posture either for offensive or defensive operations. We are now advancing toward the enemy again, being at this time within twelve miles of them."

Writing to the President of Congress (October 7, 1777) he still imputes the disaster to the fog: "It is with much chagrin and mortification I add that every account confirms the opinion I at first entertained, that our troops retreated at the instant when victory was declaring herself in our favor. The tumult, disorder, and even despair, which, it seems, had taken place in the British army, were scarcely to be paralleled; and it is said, so strongly did the idea of a retreat prevail, that Chester was fixed on as their rendezvous. I can discover no other cause for not improving this happy opportunity, than the extreme haziness of the weather."

Much controversy has arisen among writers as to the cause of failure at Germantown, but Washington's means of observation were certainly not inferior to those of any other person whatever, and in the above extracts the whole matter is clearly explained. He does not refer to the delay at Chew's house as the cause of failure. Panic struck as the British were, they would have been defeated, notwithstanding the delay at that impromptu fortress, if the fog had not occasioned the American soldiers to believe that the firing on their own side proceeded from the enemy, and that they were about to be surrounded. Hence the recoil and retreat. It was apparently a great misfortune, but it was the destiny of Washington to achieve greatness in spite of severe and repeated misfortunes.

The same opinion respecting the fog is expressed in the following extract from a letter from General Sullivan to the President of New Hampshire: "We brought off all our cannon and all our wounded. Our loss in the action amounts to less than 700, mostly wounded. We lost some valuable officers, among whom were the brave General Nash, and my two aides-de-camp, Majors Sherburne and White, whose singular bravery must ever do honor to their memories. Our army rendezvoused at Paulen's Mills, and seems very desirous of another action. The misfortunes of this day were principally owing to a thick fog which, being rendered still more so by the smoke of the cannon and musketry, prevented our troops from discovering the motions of the enemy, or acting in concert with each other. I cannot help observing that with great concern I saw our brave commander exposing himself to the hottest fire of the enemy in such a manner that regard for my country obliged me to ride to him and beg him to retire. He, to gratify me and some others, withdrew a small distance, but his anxiety for the fate of the day soon brought him up again, where he remained till our troops had retreated."

Congress unanimously adopted the following resolution on hearing of the battle of Germantown:

"Resolved, That the thanks of Congress be given to General Washington, for his wise and well-concerted attack upon the enemy's army near Germantown, on the 4th instant, and to the officers and soldiers of the army for their brave exertions on that occasion; Congress being well satisfied, that the best designs and boldest efforts may sometimes fail by unforeseen incidents, trusting that, on future occasions, the valor and virtue of the army will, by the blessing of Heaven, be crowned with complete and deserved success."

The attention of both armies was now principally directed to the forts below Philadelphia. These it was the great object of Howe to destroy, and of Washington to defend and maintain.

The loss of the Delaware frigate, and of Billingsport, greatly discouraged the seamen by whom the galleys and floating batteries were manned. Believing the fate of America to be decided, an opinion strengthened by the intelligence received from their connections in Philadelphia, they manifested the most alarming defection, and several officers as well as sailors deserted to the enemy. This desponding temper was checked by the battle of Germantown, and by throwing a garrison of Continental troops into the fort at Red Bank, called Fort Mercer, the defense of which had been entrusted to militia. This fort commanded the channel between the Jersey shore and Mud Island, and the American vessels were secure under its guns. The militia of Jersey were relied on to reinforce its garrison, and also to form a corps of observation which might harass the rear of any detachment investing the place.

To increase the inconvenience of Howe's situation by intercepting his supplies Washington ordered 600 militia, commanded by General Potter, to cross the Schuylkill and scour the country between that river and Chester, and the militia on the Delaware, above Philadelphia, were directed to watch the roads in that vicinity.

The more effectually to stop those who were seduced by the hope of gold and silver to supply the enemy at this critical time, Congress passed a resolution subjecting to martial law and to death all who should furnish them with provisions, or certain other enumerated articles, who should be taken within thirty miles of any city, town, or place in Jersey, Pennsylvania, or Delaware, occupied by British troops.