What is the origin of the term leatherneck?

The term "leatherneck" originates from the 18th century and refers to the high, stiff leather collars worn by U.S. Marines as part of their uniforms. These collars were designed to protect the neck and were associated with the Marine Corps' distinctive appearance. The term has since come to symbolize the toughness and resilience of Marines, embodying their pride and discipline.