Question: What American statesman and a retired four-star general in the United States Army has attended events at the Southern Center for International Studies? 

Context paragraphs:
William S. Wallace: William Scott Wallace, is a retired four-star general in the United States Army who served as Commanding General, United States Army Training and Doctrine Command (TRADOC) at Fort Monroe, Virginia from October 13, 2005, to December 8, 2008.  He retired from the Army on December 8, 2008.

Southern Center for International Studies: The Southern Center for International Studies (SCIS), founded in 1962, is a non-profit, private organization dedicated to international study.  Located in Atlanta, GA, it hosts several annual events, such as the Retired Secretaries of Defense Conference, and regularly hosts events for visiting dignitaries such as Tenzin Gyatso (the current Dalai Lama), Crown Prince Hassan of Jordan, President of Georgia Mikhail Saakashvili, former Secretaries of State Madeleine Albright and Colin Powell, former Secretary of the Treasury Robert Rubin, and former Secretary of Defense Donald Rumsfeld.

Colin Powell: Colin Luther Powell ( ; born April 5, 1937) is an American statesman and a retired four-star general in the United States Army.  Powell was born in Harlem as the son of Jamaican immigrants.  During his military career, Powell also served as National Security Advisor (1987–1989), as Commander of the U.S. Army Forces Command (1989) and as Chairman of the Joint Chiefs of Staff (1989–1993), holding the latter position during the Persian Gulf War.  Powell was the first, and so far the only, African American to serve on the Joint Chiefs of Staff.  He was the 65th United States Secretary of State, serving under U.S. President George W. Bush from 2001 to 2005, the first African American to serve in that position.

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.

Edwin H. Burba, Jr.: General Edwin Hess Burba, Jr. (born September 13, 1936) is a retired four-star general who served as Commander-In-Chief of the United States Army Forces Command (FORSCOM) from 1989 to 1993.  His father was also a general officer who was deputy commander of First United States Army from 1968 to 1970, and died in a plane crash.

Frederick F. Woerner, Jr.: Frederick F. Woerner, Jr. is a retired four-star general of the United States Army, former Commander of United States Southern Command, former Chairman of the American Battle Monuments Commission, and Professor Emeritus of Boston University.

Ralph E. Haines Jr.: Ralph Edward Haines Jr. (August 21, 1913 – November 23, 2011) was a United States Army four-star general who served as Vice Chief of Staff of the U.S. Army from 1967 to 1968, Commander, U.S. Army, Pacific from August 1968 to October 1970, and Commanding General, U.S. Continental Army Command (CG CONARC), from 1970 to 1973.  At his death he was the Army's oldest living four-star general and its senior retired officer.

Keith B. Alexander: Keith Brian Alexander (born December 2, 1951) is a retired four-star general of the United States Army who served as Director of the National Security Agency (DIRNSA), Chief of the Central Security Service (CHCSS) and Commander of the United States Cyber Command.  He previously served as Deputy Chief of Staff, G-2, U.S. Army from 2003 to 2005.  He assumed the positions of Director, National Security Agency and Chief, Central Security Service on August 1, 2005 and the additional duties as Commander, United States Cyber Command on May 21, 2010.

Williston B. Palmer: Williston Birkhimer Palmer (November 11, 1899 – October 11, 1973) was a United States Army four-star general who served as Vice Chief of Staff of the United States Army (VCSA) from 1955 to 1957; Deputy Commander in Chief, United States European Command (DCINCEUR) from 1957 to 1959; and was the first Director of Military Assistance, 1959 to 1962.  His brother Charles D. Palmer, was also a four-star general, the first pair of brothers in Army history to achieve this, and his grandfather, William E. Birkhimer was a Brigadier General and Medal of Honor recipient.

Dan K. McNeill: Dan Kelly McNeill (born July 23, 1946) is a retired four-star general in the United States Army.  He served as Commander, Coalition Forces, Afghanistan from 2002 to 2003 and as Commanding General, U.S. Army Forces Command (FORSCOM) from 2004 to 2007.  He then served as Commander, International Security Assistance Force (ISAF) in Afghanistan from February 1, 2007 to June 3, 2008.

Supporting paragraphs: Southern Center for International Studies Colin Powell
Answer: Colin Powell