The Green Knights began combat operations flying the F4F Wildcat and later the F4U Corsair as charter members of the Cactus Air Force and throughout the Battle of Guadalcanal arriving in October 1942.

[1] During the Pacific War, VMF-121 produced fourteen fighter aces, more than any other squadron, including Medal of Honor recipient, Major Joseph J. Foss.

In mid 1951, VMA-121 received orders to activate its reserve members and departed NAS Glenview for Marine Corps Air Station El Toro, California.

After completion of training in the Skyraider, the squadron was transported aboard the carrier USS Sitkoh Bay to Yokosuka, Japan to begin final preparations for a combat deployment to the Republic of Korea.

In June 1953 they also set a then Marine record for a single day's ordnance delivery when 16 AD-2 Skyraiders dropped 156 tons of bombs during the attack on the Sui-ho Dam.

Returning to MCAS El Toro in 1957, the squadron assumed its role in the Unit Deployment Program with scheduled rotations to Japan and traded in its AD Skyraider aircraft and joined the jet age with the F9F-8B.

Spending most of the next year at the likes of NAAS Fallon, MCAS Yuma, and NOTS China Lake, the "Green Knights" became the first squadron to complete the entire special weapons delivery syllabus.

During November 1962, the "Green Knights" deployed in their new A-4s to NAS Cecil Field in Jacksonville, Florida in response to the Cuban Missile Crisis.

The Green Knights were now capable of acquiring and destroying surface targets in any weather, day or night, with a wide variety of air-to-ground ordnance.

Arriving on Gonzo Station in the North Arabian Sea, the squadron participated in Operation Earnest Will, the escorting of reflagged Kuwaiti tankers.

Upon return to MCAS El Toro in August 1989, operational control of VMA(AW)-121 was transferred back to Commander, 3rd Marine Aircraft Wing (3rd MAW).

Returning to MCAS El Toro following the cessation of hostilities, the Green Knights resumed the unit deployment rotation and relocated to Marine Corps Air Station Miramar, California during August 1994 when custody of that installation was transferred from the Navy (as NAS Miramar) to the Marine Corps pursuant to BRAC action that also closed MCAS El Toro.

The squadron flew more than 900 combat sorties over Afghanistan in support of Operation Enduring Freedom, returning to MCAS Miramar in October 2002.