Question: What sort of art did Herbert Abrams complete using the Chief of Staff of the United States Army from 1968 to 1972 as a subjecy?

Context articles: John N. Abrams
Creighton Abrams
William Westmoreland
Charles W. Bagnal
Claude M. Kicklighter
Vice Chief of the National Guard Bureau
Robert B. Abrams
Herbert Abrams
United States Under Secretary of the Army
Leonard Wong

General John Nelson Abrams (born September 3, 1946) is a retired United States Army General who commanded the United States Army Training and Doctrine Command from 1998 to 2002.
 He is the son of former Army Chief of Staff, General Creighton W. Abrams, Jr.
Creighton Williams Abrams Jr. (September 15, 1914 – September 4, 1974) was a United States Army general who commanded military operations in the Vietnam War from 1968–72 (which saw U.S. troop strength in South Vietnam fall from a peak of 543,000 to 49,000).
 He served as Chief of Staff of the United States Army from 1972 until shortly before his death in 1974.
 In 1980, the U.S. Army named its new main battle tank, the "M1 Abrams", after General Abrams.
 The IG Farben building in Germany was also named after him from 1975 to 1995.
William Childs Westmoreland (March 26, 1914 – July 18, 2005) was a United States Army general, who most notably commanded U.S. forces during the Vietnam War from 1964 to 1968.
 He served as Chief of Staff of the United States Army from 1968 to 1972.
Lieutenant General Charles Wilson Bagnal (April 15, 1934 – June 30, 2015) was a United States Army officer.
 He was commander of the United States Army Western Command (later United States Army Pacific), from 1985 to 1989.
 Previously he was Deputy Commanding General for Training of the United States Army Training and Doctrine Command (TRADOC), Deputy Superintendent at the United States Military Academy (from 1977 to 1980), Commander of the 101st Airborne Division (1981-1983), Commander of the Officer Personnel Management Directorate for the United States Army Military Personnel Center, and Special Assistant to the Deputy Chief of Staff for Personnel.
 He is an alumnus of the United States Military Academy, United States Army Command & General Staff College, Georgia Tech, the United States Army War College and McLenaghan High School in Florence, South Carolina (class of 1952).
 He retired August 31, 1989, and later obtained his juris doctor from the University of South Carolina and practiced law.
 He resided in Columbia with his wife Patsy.
 Bagnal died on June 30, 2015 after a battle with leukemia.
Claude M. Kicklighter (born August 22, 1933) is a retired American Army Lieutenant General.
 He is a former commander of the United States Army Western Command (later United States Army Pacific), which he held from 1989 to 1991.
 He was also Director for Security Assistance for the US Army Security Assistance Center and Chief of Staff for the US Army Material Development and Readiness Command in Alexandria, Virginia, from 1981–1984 and Assistant Deputy Chief of Staff for Logistics and Director of the Army Staff for the Office of Chief of Staff in Washington, DC.
 Kicklighter was commander of the 25th Infantry Division from 1984 until being succeeded by James W. Crysel in 1986.
The Vice Chief of the National Guard Bureau (VCNGB) is the second highest-ranking officer of the National Guard Bureau, which is a joint activity of the United States Department of Defense.
 The Vice Chief of the National Guard Bureau is the second in charge of the National Guard of the United States; which is a joint reserve component of the United States Army and the United States Air Force.
 The VCNGB serves as the principal advisor to the Chief of the National Guard Bureau and the Secretary of Defense, through the Chairman of the Joint Chiefs of Staff, on matters involving non-federalized National Guard forces and on other matters as determined by the United States Secretary of Defense.
 The VCNGB also serves as the principal adviser to the Secretary of the Army, Secretary of the Air Force, the Chief of Staff of the Army, and the Chief of Staff of the Air Force, on matters relating to federalized forces of the National Guard of the United States and its subcomponents; the Army National Guard of the United States, and the Air National Guard of the United States.
Robert Bruce “Abe” Abrams (born November 18, 1960) is a four-star general in the United States Army who currently serves as the 22nd commanding general of the U.S. Army Forces Command.
 He is a 1982 graduate of the United States Military Academy where he was commissioned as an Armor officer.
 During his more than 34 years of active service he has held command and staff positions across the Army and Joint Community in Germany, the United States and Southwest Asia.
 His father was former Army Chief of Staff, General Creighton W. Abrams Jr. He assumed his current assignment on August 10, 2015.
Herbert E. Abrams (March 20, 1921 – August 29, 2003) was an American artist.
 He was one of the leading portrait artists of his era known for his style of traditional realism.
 His works included the official White House portraits of former presidents Jimmy Carter and George H.W. Bush.
 During his prolific career, he painted more than 400 portraits, including those of General William Westmoreland, playwright Arthur Miller and astronaut Edwin E. "Buzz" Aldrin Jr.
The United States Under Secretary of the Army is the second-highest ranking civilian official of the United States Department of the Army, serving directly under the United States Secretary of the Army.
 The Secretary and Under Secretary, together with two military officers, the Chief of Staff of the United States Army and the Vice Chief of Staff of the United States Army, constitute the senior leaders of the United States Army.
Leonard Wong is a Research Professor of Military Strategy (Human and Organizational Dimensions) in the Strategic Studies Institute at the U.S. Army War College, who focuses on the human and organizational dimensions of the military, and is a published author on leadership strategy.
 Wong is a registered professional engineer and holds a Bachelor of Science from the United States Military Academy, and an M.S.B.A. and Ph.D. from Texas Tech University.
 His 1992 thesis was on "The effects of cohesion on organizational performance: a test of two models" using performance data of unit battles at the U.S. Army's National Training Center, Fort Irwin, California.
 He joined the Strategic Studies Institute in July 2000 after serving 20 years in the United States Army, reaching the rank of lieutenant colonel.
 His army career included assignments teaching leadership at West Point, serving as an analyst in the Office of the Chief of Staff of the United States Army and in the Office of the Deputy Chief of Staff for Personnel, and serving as the Director of the Office of Economic and Manpower Analysis (OEMA).
 He has authored several articles, chapters, and papers on organizational issues in the Army such as downsizing, leadership, junior officer retention, professionalism, and innovation in the military.