Question: The Twelfth United States Army Group commander was the first chairman of what?

Context:
10th Armored Division (United States)
The 10th Armored Division (nicknamed "Tiger Division") was an armored division of the United States Army in World War II.
 In the European Theater of Operations the 10th Armored Division was part of both the Twelfth United States Army Group and Sixth United States Army Group.
 Originally assigned to the Third United States Army under General George S. Patton, it saw action with the Seventh United States Army under General Alexander Patch near the conclusion of the war.
Twelfth United States Army Group
The Twelfth United States Army Group was the largest and most powerful United States Army formation ever to take to the field.
 It controlled the majority of American forces on the Western Front in 1944 and 1945.
 It was commanded by General Omar Bradley with its headquarters established in London on 14 July 1944.
Operation Quicksilver (deception plan)
Operation Quicksilver was a Second World War military deception.
 Undertaken by the Allies in 1944, the operation threatened an invasion of France in the Pas de Calais region through the simulation of a large Field Army in South East England.
 Quicksilver formed part of the Operation Fortitude deception, itself part of the strategic Operation Bodyguard plan.
 The key element of Quicksilver was the creation in German minds that "First United States Army Group" (FUSAG) commanded by General George Patton supposedly would land in the Pas-de-Calais for the major invasion of Europe, after the landings in Normandy had lured the German defenders to that front.
 (FUSAG was a genuine army group headquarters which later became Omar Bradley's 12th Army Group, but was given a fictitious role and many non-existent divisions for purposes of deception.)
South German Offensive
The South German Offensive is the general name of one of the final offensives of World War II in Europe.
 The offensive was led by the Seventh and Third armies of the United States along with the First Army of France.
 Soviet troops linked up with American forces in Czechoslovakia notably in the Battle of Slivice.
 The offensive was made by the US 6th Army Group to protect the US 12th Army Group's right flank and to prevent a German last stand in the Alps.
 However German resistance was much more fierce than in the north, which slowed the 6th Army Group's progress.
 However, by the end of April, many German divisions surrendered without a fight to the advancing American forces to avoid the inevitable destruction.
 The VI Corps of the Seventh Army linked up with the US Fifth Army, which fought through Italy, in the Alps as the Third Army advanced into Austria and Czechoslovakia, where it linked up with Soviet forces advancing from the east.
 Fighting continued a few days after the Surrender of Germany on 8 May, due to German forces fighting west to surrender to the Americans instead of the Soviets.
Frederick Kroesen
Frederick James Kroesen, Jr. (born February 11, 1923) is a United States Army four-star general and was the Commanding General of the Seventh United States Army and the commander of NATO Central Army Group from 1979 to 1983, and Commanding General, United States Army Forces Command from 1976 to 1978.
 He also served as Vice Chief of Staff of the Army from 1978 to 1979.
 He commanded troops in World War II, the Korean War, and the Vietnam War, enabling him to be one of the very small number who ever was entitled to wear the Combat Infantryman Badge with two Stars, denoting active combat in three wars.
Sixth United States Army Group
The Sixth United States Army Group was an Allied Army Group that fought in the European Theater of Operations during World War II.
 Made up of field armies from both the United States Army and the French Army, it fought in France, Germany, Austria, and, briefly, Italy.
 Also referred to as the Southern Group of Armies, it was established in July 1944 and commanded throughout its duration by General Jacob L. Devers.
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.
David M. Maddox
David M. Maddox (born April 5, 1938) is a retired United States Army four-star general who served as Commander in Chief, United States Army Europe/Commander, Central Army Group (CINCUSAREUR/COMCENTAG) from 1992 to 1993; Commander in Chief, U.S. Army Europe (CINCUSAREUR) from 1993 to 1994.
 He commanded the 2nd Armored Cavalry Regiment from 1981 to 1983.
 He is a 1960 graduate of Virginia Military Institute.
 He received his MS in Applied Science (Operations Research) from Southern Illinois University in 1969.
Charles W. Bagnal
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.
Thomas T. Handy
Thomas Troy Handy (March 11, 1892 – April 12, 1982) was a United States Army four-star general who served as Deputy Chief of Staff, U.S. Army (DCSA) from 1944 to 1947; Commanding General, Fourth United States Army from 1947 to 1949; Commander in Chief, United States European Command (CINCEUR) from 1949 to 1952; Commander in Chief, U.S. Army Europe/Commander, Central Army Group (CINCUSAREUR/COMCENTAG), 1952; and Deputy Commander in Chief, U.S. European Command (DCINCEUR), from 1952 to 1954.

Answer: Joint Chiefs of Staff