So, Washington ordered inoculations for any soldiers vulnerable to the disease. A precursor to vaccination (introduced by Edward Jenner in 1798), inoculation gave the patient a milder form of smallpox with better recovery rates than if the patient had acquired the disease naturally. The procedure provided lifetime immunity from a disease with a roughly 15-33% mortality rate. In June 1778, when the Continental -Army marched out of Valley Forge, they had completed "the first large-scale, state-sponsored immunization campaign in history." By continuing the inoculation program for new recruits, Washington better maintained military strength among the regular, Continental Army troops throughout the remainder of the war. While each hut housed a squad of twelve enlisted soldiers, sometimes soldiers' families joined them to share that space as well. Throughout the encampment period, Mary Ludwig Hays and approximately 250-400 other women had followed their soldier husbands or sweethearts to Valley Forge, sometimes with children in tow. Washington once wrote that "the multitude of women in particular, especially those who are pregnant, or have children, are a clog upon every movement." Yet women on the whole proved invaluable, whether on the march or at an encampment like Valley Forge. They often earned income either by laundering clothes or by nursing troops, which kept soldiers cleaner and healthier. In turn, this made the troops appear more professional and disciplined. Lucy Flucker Knox, Catharine Littlefield "Caty" Greene, and other senior officers' wives journeyed to Valley Forge at the behest of their husbands. On 22 December, Martha Washington predicted that her husband would send for her as soon as his army went into winter quarter, and that "if he does I must go." Indeed, she did, traveling in wartime with a group of slaves over poor roads, reaching her destination in early February. Washington's aide-de-camp Colonel Richard Kidder Meade met her at the Susquehanna ferry dock to escort her into the encampment. Over the next six months, Martha hosted political leaders and military officials, managing domestic staff within the confined space of Washington's Headquarters. Valley Forge had a high percentage of racial and ethnic diversity, since Washington's army comprised individuals from all 13 states. About 30% of Continental soldiers at Valley Forge did not speak English as their first language. Many soldiers and commanders hailed from German-speaking communities, as with Pennsylvania-born Brigadier General Peter Muhlenberg. Still others spoke Scottish- or Irish-Gaelic, and a few descended from French-speaking Huguenot and Dutch-speaking communities in New York.