Thomas Cresap’s life serves as a primer on Colonial American history. In addition to being at the forefront of the contentious border conflicts between the colonies of Pennsylvania, Maryland, and Virginia, he played a part in the French and Indian War, Pontiac’s Rebellion, and the American Revolution as an officer in the Maryland militia. Cresap was an active member of the Lower House of the Maryland Assembly, the Committee of Observation, the Sons of Liberty, and the Ohio Company of Virginia. Few individuals did more, over such a long period of time, to further America’s westward expansion into the Ohio Valley than Thomas Cresap, and his personal relationships with many of the most influential men of his time helped shape the frontier. Despite all his positive contributions, Cresap was not always held in high regard by everyone. In Pennsylvania he was considered a quarrelsome and lawless ruffian known as the “Maryland Monster,” and many in the British army discounted Cresap as a “Rattlesnake Colonel.” However, settlers in Western Maryland regarded Cresap as a folk hero, and the Six Nations of the Iroquois affectionately called him “Big Spoon” for his generosity. In reality, Cresap was many things, including a frontiersman, soldier, trailblazer, ferryman, land speculator, trader, surveyor, politician, patriot, husband, and father. Drawn from Colonial land records, legislative proceedings, journals, and personal correspondence, Rattlesnake Colonel chronicles Thomas Cresap’s controversial life and narrates the complicated political and military conflicts of eighteenth-century Colonial America in a comprehensive yet understandable way.