In August 1805, as the Corps of Discovery struggled upriver toward the Rockies and morale declined because of illness, injury, and increasingly difficult river travel, Sacagawea recognized a familiar landscape and realized that her people, the Lemhi Shoshoni, were nearby. Their nearness promised food, supplies, information, and, most importantly, horses for the journey ahead. The landmark she recognized was Beaverhead Rock, about twelve miles ahead. On August 8, 1805, Meriwether Lewis wrote that she said her nation called the hill the beaver's head because its shape resembled that animal's head. About fifteen years old, Sacagawea was carrying her infant son Jean Baptiste as she helped guide the Corps of Discovery through Southern Montana.