Catharine Littlefield, known as Caty, was born on Block Island, Rhode Island, into a prominent and wealthy family. Her father, John Littlefield, was a successful merchant and landowner, and her mother, Phebe Ray Littlefield, came from a distinguished family as well.

Caty's early life was characterized by comfort and privilege. She likely received a decent education for a woman of her time, focusing on social graces and domestic skills. Block Island, being a relatively isolated community, fostered strong family and community bonds, which would influence her values later in life.

Nathanael Greene, a fellow Rhode Islander with Quaker roots (though he was later disowned for his military inclinations), visited Block Island and met Caty. They shared an immediate attraction, although their courtship was initially hindered by their families' differing social and religious backgrounds.

Caty Littlefield married Nathanael Greene, a prominent figure even at this early stage of the growing revolution. Their marriage united two ambitious and driven individuals, and despite challenges, it proved to be a strong partnership throughout their lives. The wedding took place in Coventry, Rhode Island.

The early years of their marriage coincided with the escalating tensions that led to the American Revolutionary War. Nathanael Greene quickly became involved in the military efforts, rising through the ranks, while Caty began to adjust to life as the wife of a prominent military leader, increasingly aware of the potential dangers and sacrifices involved.