D. His successes during the French and Indian War impressed Congress. George Washington served as a commander of the Virginia regiment during the war, and demonstrated strong courage and commanding ability in the face of adversity during fighting in the Ohio River Valley while he was severely ill with fever. During the French and Indian war, he gained a strong sense of strategic planning and logistics while fighting in the Appalachia wilderness that involved various skirmishes and ambushes. These proved critical to leading a continental army that would rely on guerrilla fighting in the early segments of the Revolutionary War against a much more organized British army.