Smallpox was a dreaded disease in the 18th century. It was endemic in Great Britain and, while overall less common in North America, the period of the American Revolution coincided with a very serious smallpox epidemic that started in the cities of the northeast in 1775 and spread across the continent. The soldiers of the northeastern militias and the newly formed Continental Army were at great risk, not only because life in an army camp resulted in the easy spread of such a viral infection but also because Americans were generally less likely to have developed immunity to smallpox than their British counterparts.
Inoculation against smallpox was known but was not the same as vaccination as we know it. As practiced in 1776, live smallpox virus was “inoculated” under the patient’s skin to induce a mild viral infection. People inoculated against smallpox got sick, were contagious, and sometimes died. One typically isolated oneself for some period of time when receiving a smallpox inoculation. (It was only in 1798 that a British doctor, Edward Jenner, discovered that cowpox, a harmless relative of smallpox, offered protection against smallpox without creating an actual smallpox infection, thus developing the first vaccine.)
It was at first General Washington’s policy not to inoculate soldiers because (1) they could infect each other and (2) they actually got sick, leading to concern that the enemy might know when a company was undergoing inoculation. Smallpox had hindered the Continental Army’s attack on Quebec during the winter of 1775-1776, and Washington changed his policy and started inoculating the Continental troops the following winter at Morristown, New Jersey.
It is not surprising, against this backdrop, that Benjamin Lincoln, at the time Major General of the Massachusetts militia, received a smallpox inoculation in August 1776, as evidenced by a receipt in our archives. He was preparing to leave Massachusetts the following month to lead two regiments of the Massachusetts militia to join Washington’s army in the defense of New York. The following February, he was commissioned a Major General of the Continental Army, initially at Bound Brook, New Jersey. His son, Benjamin Lincoln V, who inoculated with him, was a 21 year old law student at the time, serving under his father in the Massachusetts militia.
Joseph Gardner, the doctor who inoculated Lincoln, was in the summer of 1776 the Surgeon of Col. Thomas Crafts’ Artillery Regiment in the Massachusetts militia. Like General Lincoln, Dr. Gardner joined the Continental Army in early 1777; he is recorded as having been one of the physicians with Washington and his forces at Valley Forge in the winter of 1777-78.
After recuperating from a wound suffered during the 
Out of the Archives 