Final answer:
The U.S. Marines earned the nickname "Leathernecks" due to the high leather collar of their 1700s uniforms, which symbolizes their historic bravery in various conflicts, including World War II and earlier engagements.
Step-by-step explanation:
The nickname given to the U.S. Marines because of the high collar used by Marines in the 1700s is "Leathernecks." This term originated from the leather stock or neckpiece that was part of the Marine Corps uniform during that time. The leather stock was meant to protect the neck from saber blows and to ensure a military posture by keeping the head high.
The U.S. Marines have a storied history, exemplified by their valor and determination in various conflicts. Whether it was raising the American flag atop Mt. Suribachi during the World War II battle of Iwo Jima or their involvement in earlier conflicts like combating the Boxers in Peking, the Marines have long been a symbol of American military strength. The dedication and valor of the Marines have been recognized repeatedly, including the awarding of medals of honor to individuals such as Eugene Obregon for his heroic actions.