In this brief but consequential letter of February 6, 1777, George Washington (1732–1799) ordered Dr. William Shippen Jr. (1736–1808), the Continental Army’s chief medical officer, to inoculate all Continental troops against smallpox. The decision came at a desperate moment: the army was reeling from a brutal winter campaign, enlistments were expiring, and smallpox was spreading through the ranks. Washington recognized that the disease threatened the army more gravely than British arms—he wrote that an army ravaged by smallpox in the “natural way” would have more to dread from the disease than “from the Sword of the Enemy.” The inoculation method available then was variolation, which deliberately infected a person with live smallpox to produce a milder case and lasting immunity; it carried real risk and left patients temporarily ill and contagious, which is why Washington insisted the program be carried out quickly and “as secret as possible” to keep the enemy from learning the army was briefly debilitated. The order represented one of the first mass military inoculation campaigns in history and is often credited with preserving the Continental Army as a fighting force. This letter pairs especially well with the earlier correspondence between John and Abigail Adams (1735–1826; 1744–1818) on the same disease. In the summer and fall of 1776, while John was serving in Congress in Philadelphia, Abigail had herself and the couple’s children inoculated in Boston—a procedure she described to John in vivid, anxious detail through a series of letters. Reading the two sources side by side illustrates smallpox from sharply different vantage points: Abigail writes from the intimate perspective of a mother managing the illness of her own family, conveying fear, physical suffering, and the emotional weight of the decision, while Washington writes from the detached, strategic perspective of a commander weighing the survival of an army. Together they illustrate how a single medical threat shaped both household and national decisions during the Revolution, and how eighteenth-century Americans, despite limited scientific understanding, made bold and ultimately sound choices about disease prevention.