Operation Maui Peak, a combined regimental-sized operation which began on 6 October, ended 11 miles northwest of An Hoa, Vietnam. More than 300 enemy were killed in the 13-day operation. 

At 0622 an explosive-laden truck slammed into the BLT headquarters building in Beirut, Lebanon, where more than 300 men were billeted. The massive explosion collapsed the building in seconds, and took the lives of 241 Americans--including 220 Marines. This was the highest loss of life in a single day for Marines since D-Day on Iwo Jima in 1945. 

President Ronald Reagan, citing the threat posed to American nationals on the Caribbean nation of Grenada by that nation’s Marxist regime, orders U.S. forces to invade and secure their safety. There were approximately 1,000 Americans in Grenada at the time, many of them students at the island’s medical school. In little more than a week, Grenada’s government was overthrown. The situation on Grenada had been of concern to American officials since 1979, when the leftist Maurice Bishop seized power and began to develop close relations with Cuba. In 1983, another Marxist, Bernard Coard, had Bishop assassinated and took control of the government. Protesters clashed with the new government and violence escalated. Citing the danger to the U.S. citizens in Grenada, Reagan ordered nearly 2,000 U.S. troops into the island, where they soon found themselves facing opposition from Grenadan armed forces and groups of Cuban military engineers, in Grenada to repair and expand the island’s 

Marines from the 22nd Marine Amphibious Unit (MAU) consist­ing of 2nd Battalion, 8th Marine Regiment (2/8), Marine Medium Helicopter Squad­ron (HMM) 261, and MAU Service Sup­port Group 22 embarked aboard the ships USS Guam (LPH-9), USS Trenton (LPH-14), USS Fort Snelling (LSD-30), USS Manitowoc (LST-1180), and USS Barn­stable County (LST-1197) had been ordered to conduct non­combatant evacuation operations.

Shortly before sunrise on Oct. 25, 1983, Marines landed on Grenada. CH-46 Sea Knight transports, escorted by AH-1 Cobra attack helicopters, achieved surprise. The initial wave landed unopposed as the men of Company E, 2/8 quickly secured their landing zone and prepared to move onto their objective, Pearls Airport.

An 11,000-man 5th Marine Expeditionary Brigade left Camp Pendleton by sea for the Caribbean during the Cuban Missile Crisis. One week earlier, the entire 189,000-man Marine Corps had been put on alert and elements of the 1st and 2d Marine Divisions were sent to Guantanamo Bay to reinforce the defenders of the U.S. Naval Base. Other 2d Division units and squadrons from five Marine Aircraft Groups were deployed at Key West, Florida, or in Caribbean waters during the Cuban crisis. 

A patrol of Marines and gendarmes, led by Sergeant Herman H. Hanneken, disguised themselves as Cacos and entered the headquarters of the Haitian Caco Leader, Charlemagne Peralte, killing the bandit chief, and dispersing his followers. Sergeant Hanneken and Corporal William R. Button were each awarded the Medal of Honor.

The first African-American female colonel in the Marine Corps was promoted to that rank during a ceremony at MCAS Cherry Point, North Carolina. Colonel Gilda A. Jackson, a native of Columbus, Ohio, made Marine Corps history when she achieved the rank of colonel. She was serving as Special Projects Officer, 2d Marine Aircraft Wing at the time of her promotion.

Meeting in Philadelphia, Pennsylvania, the 2d Continental Congress used the word "Marines" on one of the earliest known occasions, when it directed General George Washington to secure two vessels on "Continental risque and pay", and to give orders for the "proper encouragement to the Marines and seamen" to serve on the two armed ships. 

Major General Keller E. Rockey, Commanding General, III Amphibious Corps, accepted the surrender of 50,000 Japanese troops in North China on behalf of the Chinese Nationalist government. 

The U.S. military, with British support, begins a bombing campaign against Taliban forces, officially launching Operation Enduring Freedom. Australia, Canada, France, and Germany pledge future support. The war’s early phase [PDF] mainly involves U.S. air strikes on al-Qaeda and Taliban forces that are assisted by a partnership of about one thousand U.S. special forces, the Northern Alliance, and ethnic Pashtun anti-Taliban forces. The first wave of conventional ground forces arrives twelve days later. Most of the ground combat is between the Taliban and its Afghan opponents.

A force of 375 Marines under command of future Commandant George F. Elliott, attacked and captured the insurgent town of Novaleta, Luzon, Philippine Islands, and linked up with U.S. Army troops. There were 11 Marine casualties. 

The 8th Marines was activated at Quantico, Virginia. Although the regiment would not see combat in Europe during World War I, the officers and enlisted men of the 8th Marines participated in operations against dissidents in Haiti for over five years during the 1920s. During World War II, the regiment was assigned to the 2d Marine Division and participated in combat operations on Guadalcanal, Tarawa, Saipan, Tinian, and Okinawa, and earned three Presidential Unit Citations. 

A Marine battalion was flown by transport helicopters to a frontline combat position for the first time, when HMR-161 lifted the 3d Battalion, 7th Marines, and its equipment, during Operation Bumblebee, northeast of Yanggu, Korea.