Question: Where is the base of the combined arms division which was supported by 4-227 ARB?

Context paragraphs:
4th Battalion, 227th Aviation Regiment: The 4th Battalion 227th Aviation Regiment is an attack reconnaissance battalion, also known as 4-227 ARB supporting the 1st Cavalry Division.  They fly the AH-64D Apache Longbow and are based at Fort Hood, Texas.

1st Armored Division (United States): The 1st Armored Division—nicknamed "Old Ironsides"—is a combined arms division of the United States Army.  The division is part of III Corps, with its base of operations in Fort Bliss in El Paso, Texas.  It was the first armored division of the U.S. Army to see battle in World War II.

Combined Arms Research Library: The Combined Arms Research Library (CARL) at Fort Leavenworth, Kansas is a United States Army library which supports the United States Army Command and General Staff College.  Its collection of over 300,000 books covers all aspects of military science: joint and combined operations; tactics and doctrinal development; leadership, intelligence, weapons, equipment, and training.  The Archives and Special Collections house a unique collection of over 200,000 items and the documents collection consists of another 250,000.  Each year, the CARL reference staff answers some 30,000 queries for soldiers, faculty and staff at Fort Leavenworth, Kansas and throughout the world via the Defense Digital Library Reference Service.  Scholars, writers and the DoD community use the Combined Arms Research Library's archival materials, extensive research materials, and historical documents.  The Combined Arms Research Library is one of the largest and most well respected libraries in the Army and was named the 2007 Federal Library of the Year by the Federal Library and Information Center Committee (FLICC).

6th Division (Singapore): The 6th Singapore Division commonly known as 6th Division is a combined arms division of the Singapore Army.

3rd Division (Singapore): The 3rd Singapore Division commonly known as 3rd Division is a combined arms division of the Singapore Army.

1st Infantry Division (United States): The 1st Infantry Division is a combined arms division of the United States Army, and is the oldest continuously serving in the Regular Army.  It has seen continuous service since its organization in 1917 during World War I.  It was officially nicknamed "The Big Red One" (abbreviated "BRO") after its shoulder patch and is also nicknamed "The Fighting First".  However, the division has also received troop monikers of "The Big Dead One" and "The Bloody First" as puns on the respective officially-sanctioned nicknames.  It is currently based at Fort Riley, Kansas.

Moscow Higher Military Command School: The school was formed in December 15, 1917, by order of Vladimir Lenin as the "1st Moscow machine-gun school".  In October 1941, the school was renamed after the Supreme Soviet of the RSFSR.  In June 1958 the school was transformed into the Moscow Higher Combined Arms Command School.  The school had a training period of four years.  On May 7, 1965, the school was awarded the Order of Lenin.  On February 21, 1978, the school was awarded the Order of the October Revolution.  In 1995, the 4-year training period was replaced with a training period of 5 years.  In August 2004, the university was renamed the Higher Professional Education Institution of the Ministry of Defense of the Russian Federation (and was retited the "Moscow Military Command Training School").  In 2010, the school was integrated into the Combined Arms Academy of the Russian Armed Forces.  In 2017, the Military Institute was removed from the Combined Arms Academy and was renamed again as the Moscow Higher Military Command School (Combined Arms).

Combined arms: Combined arms is an approach to warfare which seeks to integrate different combat arms of a military to achieve mutually complementary effects (for example, using infantry and armor in an urban environment, where one supports the other, or both support each other).  According to strategist William S. Lind, combined arms can be distinguished from the concept of "supporting arms" as follows:

1st Cavalry Division (United States): The 1st Cavalry Division ("First Team") is a combined arms division and is one of the most decorated combat divisions of the United States Army, as well as the other four branches of the U.S. military.  It is based at Fort Hood, Texas.  It was formed in 1921 and served during World War II, the Korean War, the Vietnam War, the Persian Gulf War, with the Stabilization Force in Bosnia-Herzegovina, in the Iraq War, in the War in Afghanistan and in Operation Freedom’s Sentinel.  As of 2017, the 1st Cavalry Division is subordinate to III Corps and is commanded by Major General John C. Thomson III.

9th Division (Singapore): The 9th Singapore Division/Infantry commonly known as 9th Division is a combined arms division of the Singapore Army.

Supporting paragraphs: 4th Battalion, 227th Aviation Regiment 1st Cavalry Division (United States)
Answer: Fort Hood, Texas