Question: What was the codename for the battle where the 9th Amphibian Tractor Battalion supported the 6th Marine Division?

Context paragraphs:
3rd Battalion, 24th Marines: 3rd Battalion, 24th Marines (3/24) was a reserve infantry battalion in the United States Marine Corps.  The battalion was first formed in 1943 for service in the Pacific Theater of Operations during World War II, taking part in a number of significant battles including those at Saipan and Iwo Jima before being deactivated at the end of the war.  In the early 1960s, the unit was reactivated as a reserve battalion.  It was located throughout the Midwestern United States and consisted of approximately 800 Marines and Sailors.  The battalion was part of the 24th Marine Regiment and the 4th Marine Division.  Recent operations included tours in Iraq and Afghanistan.  On May 19, 2013, the battalion was deactivated (retired) as a part of 2013 Marine Corps Force Restructuring, along with the 24th Marine Regiment.  3/24 personnel were reallocated to 23rd Marine Regiment, with the majority of the companies becoming 3rd Battalion, 23rd Marines.

Scout and Sniper Company (6th Marine Division): The Scout and Sniper Company of 6th Marine Division was the division reconnaissance asset for the regimental commanders.  It was created from former Marine Raider Major Anthony "Cold Steel" Walker to form a scout company from Company H from out of one of the regiments of 6th Marine Division.  The Scout Company deactivated, along with 6th Marine Division, after the end of World War II.

9th Amphibian Tractor Battalion: The 9th Amphibian Tractor Battalion ("9th Amtrac Battalion") is an inactive amphibious assault battalion of the United States Marine Corps.  The battalion supported the 6th Marine Division during the Battle of Okinawa in World War II.

5th Battalion, 11th Marines: 5th Battalion 11th Marines (5/11) is a High Mobility Artillery Rocket System HIMARS battalion of four Firing Batteries and a Headquarters Battery.  The battalion is stationed at Marine Corps Base Camp Pendleton, California.  It is the first active duty HIMARS Unit in the Marine Corps.  They fall under the command of the 11th Marine Regiment and the 1st Marine Division.  This is the only battalion in the 11th Marine Regiment not using the M777A2 lightweight howitzer.

9th Marine Expeditionary Brigade (United States): The 9th Marine Expeditionary Brigade was a United States Marine Corps unit.  5th Tank Battalion, 5th Marine Division deployed with 9th MEB, later assigned to 1st Marine Division as a reinforcement Battalion.

3rd Battalion, 4th Marines: 3rd Battalion, 4th Marines (3/4) is an infantry battalion of the United States Marine Corps.  Nicknamed "Thundering Third".  The most recent leader Lt. Col. B. Middleton's radio callsign is "Darkside".  They are based at the Marine Corps Air Ground Combat Center, Twentynine Palms, California, and consist of approximately 1,000 Marines.  The unit currently falls under the command of the 7th Marine Regiment, 1st Marine Division, but — along with its two sister battalions — is hosted by the 3rd Marine Division, at Camp Schwab in Okinawa, Japan, when training in jungle warfare.  The 3rd falls under the 4th Marine Regiment at such times.

2nd Battalion, 28th Marines: The 2nd Battalion, 28th Marine Regiment (2nd Battalion, 28th Marines) is an infantry battalion of the United States Marine Corps.  The battalion (inactive since the Vietnam War) which is part of the 28th Marine Regiment, 5th Marine Division, fought in the Battle of Iwo Jima during World War II.  Six Marines of E Company, 2nd Battalion, 28th Marines were featured in the historical photo by Joe Rosenthal of the U.S. flag raising on top of Mount Suribachi.

3rd Infantry Brigade, 2nd Infantry Division: At the time of its activation, the 2nd Infantry Division was composed of the 3rd Infantry Brigade, which included the 9th Infantry Regiment; the 23rd Infantry Regiment and the 5th Machine Gun Battalion; the 4th Marine Brigade, which consisted of the 5th Marine Regiment, the 6th Marine Regiment and the 6th Machine Gun Battalion; 2nd Brigade of field artillery; and various supporting units.

3rd Battalion, 9th Marines: The 3rd Battalion, 9th Marines (3/9) is an infantry battalion of the United States Marine Corps.  Formed during World War I it served until the early 1990s when it was redesignated as 3rd Battalion, 4th Marines (3/4) during a realignment and renumbering of the Marine Corps' infantry battalions, following the deactivation of the 9th Marine Regiment.  The 3rd Battalion, 9th Marines was initially a subordinate unit of the 9th Marine Regiment, 3rd Marine Division, but was later operationally transferred to the 1st Marine Division as a subordinate unit of the 7th Marine Regiment where it remained until its redesignation as 3/4.

Battle of Okinawa: The Battle of Okinawa (Japanese: 沖縄戦 , Hepburn: Okinawa-sen ) (Okinawan: 沖縄戦 , "Uchinaa ikusa " ), codenamed Operation Iceberg, was a major battle of the Pacific War fought on the island of Okinawa by United States Marine and Army forces against the Imperial Japanese Army and included the largest amphibious assault in the Pacific War during World War II, the April 1, 1945, invasion of Okinawa itself.  The 82-day battle lasted from April 1 until June 22, 1945.  After a long campaign of island hopping, the Allies were planning to use Okinawa, a large island only 340 mi away from mainland Japan, as a base for air operations for the planned invasion of the Japanese home islands.

Supporting paragraphs: 9th Amphibian Tractor Battalion Battle of Okinawa
Answer: Operation Iceberg