From John Hennessy:
It was the largest single hospital the Fredericksburg area has ever seen–more than 400 tents and 4,000 patients perched on a windy flat on what we know today as Marlborough Point in Stafford County. The Union army in 1863 called it Windmill Point Hospital. Work on the hospital started three weeks after the Battle of Fredericksburg, but the purpose of the place was not to care for the wounded. Rather, the hospital became the destination for the sick of the Army of the Potomac–all of them emerging from the vast encampment in southern Stafford and western King George counties. “The tents are in elevated ground,” wrote one hospital worker, “and it looks like an immense camp meeting; but, unhappily, it is composed of sick soldiers, and there is more crying than singing.” [Letter of O.P. Case, Hartford Daily Courant, February 1, 1863.]
Wrote another, “It was such an hospital as never before nor since was seen in the Army of the Potomac. On a broad level plain, not long since a cultivated field, was a city of tents, regularly laid out in immense diamond-shaped inclosures. Eight army corps, each with its three divisions, were represented here.” [United States Christian Commission for the Army and Navy: Work and Incidents, Second Annual Report. 1864. p. 35.]
Harriet Eaton, a relief worker from Maine, found the place objectionable in its early weeks of existence. To reach the hospital, she and everyone else had to take the train to Aquia Landing, then a ferry three miles down the Potomac to the hospital landing. When she departed the ferry, she first had to negotiate her way through 2,000 head of cattle, awaiting slaughter. In the hospital, she found conditions shocking: “Nothing but hard tack and salt pork for 4,000 poor sick men! …No kettles to cook with, not even wash basins for washing, nothing, nothing, nothing, but indifference.” She saw tragic significance in the neglect: “When a man is sick, no longer effective as a soldier, what does the government care for him!” [Jane Schultz, ed., The Birthplace of Souls: The Civil War Nursing Journal of Harriet Eaton, p. 110, entry for January 24].
One man wrote that in the first weeks of its operation, the hospital “was the worst place I ever witnessed. Sick men landing there by thousands—placed in tents—in those terrible cold nights, with no wood for days. Many had their feet frozen, all suffered intensely; 23 men were laid in their shallow graves in a single day.”
With the ascension of Hooker to army command and the hand of Jonathan Letterman in control of all things medical in the army, the chaos of those cold January weeks soon yielded to order and efficiency. Windmill Point Hospital would in its six months of existence provide care for thousands of sick soldiers (and after Chancellorsville, many wounded ones). A Connecticut officer who visited the hospital in late February found it a marvel.
“The Hospital at Aquia Landing [Windmill Point] is worth crossing the Atlantic to see. It has been started and completed within four week, and is the place where now the sick of the Army of the Potomac are sent. A “hospital tent’ is a tent like an officers’ or wall tent, only more than three times as large. The space within it is equal to a good sized drawing room. More than  of these tents, white as the driven snow, pitched in long streets of more than a quarter of a mile, and supplied with every convenience and comfort, compose this hospital. From the hill which I was descending to reach it, it presented in the evening twilight one of the most beautiful of sights. You will form some estimate of its size, when I tell you that between nine and ten thousand people occupy it. It lies on the table land of a promontory, called Windmill Point, jutting out into the Potomac, where there is a fine view of a beach of the river, and is bounded behind and on the sides by high wooded hills. As I went along through the streets…one gets lost quicker than in an unfamiliar city from the perfect sameness of everything… Everything was in perfect order—stables in tents for the horses, out-houses in tents, kitchens, store rooms, parlors and surgeries in tents—and it seemed like a huge camp of Bedouins. For the first time in a long time, I saw ladies flitting about, nurses belonging to the sanitary commission, who come and go as occasion requires.” [Hartford Daily Courant, March 3, 1863.]
The hospital remained in operation until the army evacuated the Fredericksburg area in early June 1863.