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?

full_context: Document 1: George H. W. Bush: George Herbert Walker Bush (born June 12, 1924) is an American politician who was the 41st President of the United States from 1989 to 1993 and the 43rd Vice President of the United States from 1981 to 1989. A member of the Republican Party, he was previously a congressman, ambassador, and Director of Central Intelligence. He is the oldest living former President and Vice President. Previously known as simply "George Bush", since 2001, Bush has often been referred to as "George H. W. Bush", "Bush 41", "Bush the Elder", or "George Bush Senior" to distinguish him from his eldest son, George W. Bush, the 43rd President of the United States.
Document 2: Creighton Abrams: 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.
Document 3: Matthew Ridgway: General Matthew Bunker Ridgway (March 3, 1895 – July 26, 1993) was the 19 Chief of Staff of the United States Army. He served with great distinction during World War II, where he was the Commanding General (CG) of the 82nd Airborne Division, leading it in action in Sicily, Italy and Normandy, before taking command of the newly formed XVIII Airborne Corps in August 1944, holding this post until the end of the war, commanding it in the Battle of the Bulge, Operation Varsity and the Western Allied invasion of Germany.
Document 4: Robert W. RisCassi: Robert William RisCassi (born January 18, 1936) is a retired United States Army four-star general who served as Vice Chief of Staff of the United States Army (VCSA) from 1989 to 1990; Commander in Chief, United Nations Command/Commander in Chief, ROK/U.S. Combined Forces Command/Commander, U.S. Forces Korea/Commanding General, Eighth United States Army (CINCUNC/CINCCFC/COMUSFK/CG EUSA) from 1990 to 1992; and Commander in Chief, United Nations Command/Commander in Chief, ROK/U.S. Combined Forces Command/Commander, United States Forces Korea (CINCUNC/CINCCFC/COMUSFK) from 1992 to 1993.
Document 5: Harold Keith Johnson: Harold Keith "Johnny" Johnson (February 22, 1912 – September 24, 1983) was Chief of Staff of the United States Army from 1964 to 1968. Regarded as a premier tactician, Johnson became skeptical that the level of resources given to the Vietnam War, much of which went into 'find, fix, and destroy the big main force units' operations, could deliver victory. Johnson came to believe that the Communist forces held a trump card, because they controlled whether there were engagements with US forces, giving an option to simply avoid battle with US forces if the situation warranted it.
Document 6: Alan Shepard: Rear Admiral Alan Bartlett Shepard Jr. (November 18, 1923 – July 21, 1998) was an American astronaut, naval aviator, test pilot, and businessman.
Document 7: Raymond T. Odierno: Raymond Thomas "Ray" Odierno ( ; born 8 September 1954) is a retired United States Army General who served as the 38th Chief of Staff of the Army. Prior to his service as Chief of Staff, Odierno commanded United States Joint Forces Command from October 2010 until its disestablishment in August 2011. He served as Commanding General, United States Forces – Iraq and its predecessor, Multi-National Force – Iraq, from September 2008 through September 2010. Before then, he served as Commanding General, III Corps, from May 2006 to May 2008. Odierno is the twelfth American military officer to command at the Division, Corps, and Army level during the same conflict and only the second with this distinction since the Vietnam War. Before commanding III Corps, he served as Assistant to the Chairman of the Joint Chiefs of Staff in Washington, where he was the primary military adviser to Secretary of State Condoleezza Rice from 3 November 2004 to 1 May 2006.
Document 8: Herbert Abrams: 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.
Document 9: Daniel Greene (artist): Daniel E. Greene PSA, NA, AWS (born 1934) is an American artist who works in the media of pastels and oil painting. The Encyclopædia Britannica considers Mr. Greene the foremost pastelist in the United States. His paintings and pastels are in over 700 public and private collections in the United States and abroad. Highly regarded as a portrait artist, his subjects have included leaders of Government, Banking, Education and Industry. Some of his sitters include First Lady Eleanor Roosevelt, Ayn Rand, Astronaut Walter Schirra, William Randolph Hearst, “Wendy’s” founder Dave Thomas, Commentator Rush Limbaugh, Composer Alan Menken, Bryant Gumbel and Bob Schieffer of CBS TV. Governmental Portraits include Secretary of Agriculture Ann Veneman, Governor Paul Laxalt of Nevada, Governor Gerald Baliles of Virginia, Governor Benjamin Cayetano of Hawaii, and Governor Fob James of Alabama. Business sitters include the chairmen of the boards of Honeywell, Coca-Cola Company, Dupont Corporation, Endo Pharmaceuticals, American Express, The New York Stock Exchange and IBM. Mr. Greene has also painted the Deans, Presidents and Benefactors of Tufts, Duke, Columbia, North Carolina, West Point, Delaware, Penn State, New York, Princeton, Rutgers, Yale and Harvard Universities.
Document 10: Peter Schoomaker: Peter Jan Schoomaker (born February 12, 1946) is a retired four-star general of the United States Army and served as the 35th Chief of Staff of the United States Army from August 1, 2003 to April 10, 2007. Schoomaker's appointment as Chief of Staff was unique in that he was recalled and came out from retirement to assume the position. Schoomaker voluntarily retired from the Army for the second time in 2007 after completing the full four-year term as Chief of Staff.
Document 11: Mort Künstler: Mort Künstler (born August 28, 1927) is an American artist known for his illustrative paintings of historical events, especially of the American Civil War. He was a child prodigy, who, with encouragement from his parents, became a skilled artist by the time he was twelve. Today he is considered the "best-known and most respected historical artist in the country."
Document 12: Michael Abramson: Michael Abramson (1948–2011) was a Chicago photographer who produced a large body of artistic and commercial photography. He earned a Bachelor's degree from the Wharton School of Business, but his life took a different direction when he was accepted at the Institute of Design at the Illinois Institute of Technology in Chicago, and subsequently earned a Masters in 1977. His thesis, "Black Night Clubs of Chicago's South Side," was a reflection and analysis of the photographs he took of patrons and performers in nightclubs on Chicago's south side during the mid-1970s. Abramson's work has often been compared to the 1920s Paris photographer Brassaï (1899-1984). Many of Abramson's south side prints were later published in a photography book / 2 LP record set entitled "Light on the South Side" (2009), by Chicago music recording company Numero Group. The collection of music featured on the LPs are blues songs by mostly Chicago recording artists, and reflect what was actually playing on the jukeboxes in these clubs at the time. A slideshow was created using Abramson's photographs and the music from the LP.
Document 13: William Westmoreland: 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.
Document 14: Robert B. Abrams: 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.
Document 15: Omar Bradley: General of the Army Omar Nelson Bradley (February 12, 1893 – April 8, 1981), nicknamed "Brad", was a highly distinguished senior officer of the United States Army during and after World War II. Bradley was the first Chairman of the Joint Chiefs of Staff and oversaw the U.S. military's policy-making in the Korean War.
ground_truth: portrait