What was the purpose of the Marine Corps' action in Lebanon in 1958?

The purpose of the Marine Corps' action in Lebanon in 1958 was primarily to provide support for the Lebanese government, which was facing internal strife and instability. The U.S. deployed Marines to Lebanon in response to the political turmoil and to prevent the spread of conflict that could potentially involve other nations in the region. This intervention was aimed at stabilizing the situation, ensuring the integrity of Lebanon’s government, and protecting American interests in the Middle East during a time of heightened tensions.

The focus on supporting the local governmental forces directly aligns with the correct answer, as the Marines were deployed to assist the Lebanese president and maintain order during a period of civil unrest.