From Benjamin Rush
Philadelphia May 13th 1777.
I have just now learned from General Mifflin that your Excellency intends to take the field in a few days. I hope your Excellency will excuse the liberty I am about to take in Suggesting that your troops will probably suffer from being so early exposed in an encampment. The variable weather of the Spring and fall have always been found much more destructive to the health of an Army than the uniform heats of Summer or colds of Winter. One of the greatest Authorities in physic Sir John Pringle1 tells us that the difference in the proportion of sick in an Army in the latter end of April, and the middle of may is as 1 to 32 in the former and 1 to 36 in the latter case. The Weather in that part of Germany where the Above Observation was made is generally as warm in the middle of may as it is with us on the 1st of June. From the effects of the ordinary winds and weather in the month of may in the middle states upon the constitution, I am inclined to think that the proportion of sick in our Army should they now take the field would be considerably greater than that mentioned by Sir John Pringle. The single circumstance of several thousands of them having been so lately enfeebled by the Small pox would add greatly to the number of sick. If your Excellency can possibly delay encamping your men a few weeks longer I am sure you will save the lives of many hundreds by it, besides retaining as many more in your Service who might Otherwise be rendered unfit for duty during the Summer.
With sincere wishes that you may begin and close the campaign with much honor to yourself, and lasting Advantages to our country, I have the honor to be with great regard your Excellency’s most Obedt Hble Servant
1. John Pringle (1707–1782), with whom Rush had become personally acquainted during his 1768–69 visit to London, gained great fame as a reformer of military medical practices and camp sanitation during his service as physician to the commander of the British forces on the European continent from 1742 to 1744 and physician general to the British army from 1744 to 1758, and his book Observations on the Diseases of the Army (London, 1752) became a medical classic. Pringle was named physician to the queen in 1761 and physician to the king in 1774. He received a baronetcy in 1768, and he served as president of the Royal Society from 1772 to 1778.