Captain Kimball, Continental Army, slowed his horse to a walk and turned off the dusty highway into the cobbled High Street of Port Chatham. A group of happy, mud-splashed children were sailing their toy boats in the refuse gutter that ran down the center of the street, and a fastidiously dressed merchant, his silk stockings and black breeches shiny new, gave the laughing children a wide berth as he hurried past. Halfway up the street a servant wench, with her sleeves rolled up to her plump elbows, was kneeling on the front steps of an oyster-shell-plastered house, scouring the pink marble threshold with handfuls of fine river sand. (p. 11)
Summary: Captain Jonathan Kimball is on an intelligence mission for General George Washington. It is 1778. Jonathan is supposed to meet up with Elizabeth Ladd, who is the daughter of a prominent Philadelphian ship owner, and pose as a family servant in order to gather information about the British army that is occupying Philadelphia. Jonathan and Elizabeth have to work out some friction because, despite both supporting the American cause, they have very different perspectives on the war. Jonathan, a solider in the army, sees himself as a die-hard Rebel; Elizabeth, however lives in an occupied city, in which day-to-day life requires an attitude of cautious courtesy and deal-making toward the British. Both kinds of people are in fact essential to the war effort, although it takes some time for Jonathan fully to grasp how, and he only really begins to do so when Elizabeth risks her life at a masquerade ball hosted by the British soldiers in order to gather information that will save General La Fayette from an ambush at Barren Hill. Elizabeth, for her part, having lived in a city in which the British soldiers are primarily a police presence, does not fully appreciate the complications of war, and it's only exposure to its difficulties and dangers that brings her around.
George Washington was in general a competent commander, but in the area of military intelligence, he was ahead of his time. Faced with a larger and much, much better-supplied enemy, Washington made extensive use of his primary advantage, which was the ability to obtain information about the other side. The Continental Army under Washington used and often pioneered an extensive array of espionage practices; while it was nothing on the scale and sophistication of modern military intelligence, it was nonetheless often quite ingenious. Thus making the tale primarily a spy story rather than a battle story works very well; two major battles -- Barren Hill and Monmouth -- play a significant role in the story, especially the second, but the primarily plot is carried by the spy games.
The British were also not slouches at military intelligence, and one of the major problems faced by the Continental Army is the difficulty of knowing who is a traitor and who is not. A significant portion of the book is concerned with the possible treason of General Charles Lee, at this point the second-in-command. Historically, it's unclear whether and how far he was actually a traitor; when he was captured once, he gave the British a plan for defeating the Continental Army, but some have argued that it was a clumsy attempt to feed the British misinformation. What is very certain is that he did not like Washington. Lee had been widely regarded as the preferred choice to lead the Continental Army; the reason the command went to Washington was that Washington, unlike Lee, was born in the colonies, and Lee, a proud man, seems to have resented Washington for the rest of his career for it. The book takes a dark view of him, and it is clear from almost the beginning that he is selling out the Continental Army to the British. The difficulty Washington faces with regard to him has multiple aspects: first, he has no certainty of Lee's treachery; second, even if he had, he has no evidence of it; third, even if he had some evidence, Lee's political connections and general support are so good that any evidence would need to amount to proof; and fourth, Washington himself, constantly having to fend off character assassinations from other sources, and not particularly well supported in Congress at this point, has to move very cautiously. Thus Washington ends up having to build his strategies both on the assumption that Lee is loyal and on the assumption that he is not.
The book is a very smooth read; both the spycraft and the battles are described well. It does an extremely good job in portraying how divided the Americans were, and also in showing how often significant events were affected by the right person in the right place making the right choice. The title, Farewell to Valley Forge, is at first a bit odd, because remarkably little of the book has anything to do with Valley Forge. But I think the point of it is that the book describes a transition point, from the American army being a large revolt with Valley Forge as one of its holing-up places as it tried to pull itself together, to an army capable of winning a major battle at the Plains of Monmouth against a superior army. It's not just a farewell to the encampment; it's a farewell to being the kind of army it was in the encampment.
Washington leaned back in his chair; pushing his long legs under the table, he folded his arms and spoke seriously. "You and I, William, have no desire other than to live under a civil authority free from military domination. But to win that freedom by means of military domination of the Congress is to admit that the goal we seek is unattainable."
"Even so, sir, others, besides the English, wonder how long it will be before you say, 'Satis superque!'"
"It will not be said by me." Washington's eyes glittered and his jaw firmed. "The Congress my request, nay, demand, my sword, but I will be neither taunted nor insulted nor wheedled into saying, 'It is enough.'" The Commander-in-Chief reached out and tapped the pile of correspondence tied with the tape and daubed with the sealing wax that proclaimed it came from the Congress. "This is a symbol, William. If ever we expect to establish a government of these separate states that will be answerable only to the people -- the acceptance of public censure will be necessary for its continuance. Who am I then, to escape it? Since I have accepted the trust thrust upon me, I must needs accept the criticism that it brings -- merited or otherwise." (p. 136)
David Taylor, Farewell to Valley Forge, J. B. Lippincott Company (New York: 1955).