Reports that in a previous letter to Lucy, he gave an account of the Battle of Brandywine. Relates that his army came in sight of the enemy, when a pouring rain ruined their cartridges. Describes how his army followed the British from across the Schuylkill River, and the British eluded them, intending to enter Philadelphia: They have declin'd to combat our army and have taken possession of the prize for which we both contended. Reports that American Generals [Anthony] Wayne and [William] Smallwood were attacked on 20 September (later known as the Battle of Paoli or the Paoli Massacre). Comments on the American soldiers' lack of shelter and supplies, which they endured with the perseverance and patience of Good Soldiers. Of losing Philadelphia, writes, I consider the loss of Philadelphia as only temporary to be recovered when expedient... Notes that the British will need to start shipping to and from Philadelphia in order to maintain their hold on the city. Reports that his brother William endures the hardships of this campaign surprisingly well.

Written in camp twenty miles from Philadelphia, Pennsylvania. Expresses his happiness that Lucy has spent time in Newburyport, Massachusetts: The Gentlemen there with whom I am acquainted, are in my opinion some of the most virtuous public spirited, patriots on the Continent. Reports that British General William Howe might be sailing toward the Chesapeake Bay. Disbelieves the Chesapeake is Howe's target. Asserts instead that Howe intends to sail for the North River (the Hudson) or Philadelphia. Discusses Howe's movements and comments on the extremely hot weather. Referring to British General John Burgoyne, writes Mr. Burgoyne will push himself untill he finds a stone wall to break his head against- I hope that will not be too soon untill all parts of the Machine may harmonize which is to work his destruction... Referring to his brother William, writes Master Bill bears the fatigues of the Campaign like a soldier and they are not very few...

Reports, The enemy have manoevr'd us to this place... and after all gave us the slip... this is now the third day of their departure with a fine a wind as ever blew to carry them to New York and so up the North River [the Hudson]-- this must be their great object, and however appearances may have been against it- I could never account why it was not done- Thank God our force there is pretty respectable, and if they can hold out only till we get there... our forces will all be put in motion that way. Emphasizes that General George Washington could not have acted otherwise, for had he not moved to Philadelphia, the British would have taken the city. Predicts Howe's force is smaller than previously imagined based on the British General's hasty departure. Apologizes for the brevity of this letter.

A brief and hurried letter to let Lucy know that he is well and in good spirits. Displays optimism about the war, although at the time the American forces were being driven from New York City by the British.

Knox writes, the shortness of your two last letters were not very agreable [sic] to me... Discusses the Battle of Ticonderoga (2-6 July 1777): We have received... news of the evacuation of Ticonderoga pregnant in my opinion with the most disagreable [sic] consequences of any thing during the War... Mentions Generals John Burgoyne (British), Arthur St. Clair (American), and Philip Schuyler (American). Refers to a wagon of supplies Lucy sent to him. Wishes his brother William would not join the Army, but would instead remain in Boston, serving as a disinterested friend and protector for Lucy. Expects General William Howe to combine forces with Burgoyne at an unspecified point along the North River (the Hudson). Mentions that Mrs. Greene (Catherine Littlefield Greene, wife of General Nathanael Greene) arrived several days before. Discusses a letter he sent to John Hancock, President of the Continental Congress, inquiring if Congress intended to appoint Phillippe du Coudray in command of the Continental Artillery. Reports that Congress resolved that Knox's letter was an infringement on the Liberties of the people.

Laments not being able to return to Lucy when he had hoped to. Praises Lucy at length and reaffirms his love for her. Notes that this is only the fourth letter he has been able to write to her in the two months they have been apart, and explains why his letter of 5 December 1775 was so short (see GLC02437.00215). Comments on the weather and the lack of snow, which impeded his plans to transport artillery from Fort Ticonderoga to Cambridge, Massachusetts. Mentions that his brother William Knox is now at Lake George preparing the sleds for the transport. Describes his travels. Comments favorably of the city of New York in comparison to Boston, but criticizes the people's pride, conceit, profaneness, and Toryism. Mentions the low population and poverty of the area between New York City and Albany. Favorably assesses Albany, New York and speculates that, because of its access to the western territories, it will one day be if not the Capital yet nearly to it of America. Criticizes treatment of American prisoners of war by the British, citing Richard Prescott's abuse of Ethan Allen. Prescott was captured by the Americans on 17 November 1775, and Knox remarks that he and other prisoners were being sent from Albany to Pennsylvania. Comments on letters between generals George Washington and William Howe in which Washington vows to treat Prescott as Allen was treated. Comments on his impression of the British prisoners.

Reports that the British have landed at Head of Elk, Maryland (present day Elkton), twenty miles from Knox's location. Writes, ...we shall remain here a few days and if they will not come to us we shall go to them... it is suppos'd the enemy intend for Philadelphia if so they will meet with a stout opposition. Relates he is serving on a Court Martial. In closing, writes my soul is intimately connected with yours.