Many think of the United States Marine Corps as a second land army, and while it has been employed in that capacity, it is foremost a naval expeditionary force able to seize, secure, and defend advanced naval bases in support of major campaigns. The Corps dates back to the Revolutionary War, but while they served in the conflicts of the 19th century, they are famed for their part in the wars of the 20th century. On the Western Front in World War I they were bloodied at Belleau Wood. Between the wars the Corps developed amphibious tactics which were employed to great effect during the Pacific island campaigns during World War II including the infamous battles of Peleliu, Iwo Jima and Okinawa. The names of the Corps are forever entwined with the battles of Inchon and Chosin Reservoir in Korea, and Hue and Khe Sanh in Vietnam. The US Marines have continued their expeditionary role to this day, undertaking not only combat operations but also peacekeeping, peace enforcement, humanitarian relief, and short-notification/limited-duration contingency operations.This concise history charts the evolution of the Corps as it has adapted to changing combat over two centuries.