Question: When was the former American college football coach which  Bruce Chambers was his stff born 

Context paragraphs:
Larry Kehres: Larry Kehres (born September 7, 1949) is a college athletics administrator and former American football player and coach.  He is the athletic director at the University of Mount Union, formerly known as Mount Union College, in Alliance, Ohio.  Kehres was the head football coach at Mount Union for 27 seasons, from 1986 through the 2012 season.  In May 2013, Kehres retired with a record of 332–24–3 as head coach of the Mount Union Purple Raiders football team, and a winning percentage of , the highest in college football history.  Kehres also has the most national titles (11: 1993, 1996–1998, 2000–2002, 2005–2006, 2008, 2012), conference titles (23), and unbeaten regular seasons (21) of any coach in college football history.  His Purple Raiders set the National Collegiate Athletic Association (NCAA) football record for most consecutive victories with 55, running from 2000 to 2003.  He was succeeded as head football coach by his son, Vince.

Floyd Keith: Floyd A. Keith (born August 22, 1948) is a former American football coach.  He served as the head football coach at Howard University from 1979 to 1982 and at the University of Rhode Island from 1993 to 1999, compiling a career college football record of 46–70–2.  He is the Executive Director of the Black Coaches and Administrators.  He served as a college football coach for 30 years (1970–1999).

Mack Brown: William Mack Brown (born August 27, 1951) is a former American college football coach.  He was most recently head football coach of the Texas Longhorns football team of the University of Texas at Austin.  He is currently a college football commentator for ESPN.

Tom Osborne: Thomas William Osborne (born February 23, 1937) is a former American football player, coach, college athletics administrator, and politician from Nebraska.  He served as the head football coach at the University of Nebraska football team for 25 years, from 1973 to 1997.  Osborne was one of the most successful coaches in American college football history, with a career record of 255–49–3, 13 conference championships, and three national championships.  He was inducted into the College Football Hall of Fame as a coach in 1999.  Osborne was later elected U.S. Representative from Nebraska's 3rd congressional district, as a Republican.  He served three terms, from 2001 to 2007.  In 2007, he returned to the University of Nebraska as athletic director (AD).  He retired as AD in January 2013.

Dick Bestwick: Dick Bestwick (born August 18, 1930) is a former American football player, coach, and college athletics administrator.  He served as the head football coach of the University of Virginia from 1976 to 1981, compiling a record of 16–49–1.  A native of Grove City, Pennsylvania, he played college football at the University of North Carolina at Chapel Hill, graduating from the school in 1952.  Bestwick received his Masters in Education from Pennsylvania State University.  Prior to his tenure at Virginia, Bestwick spent 1954 to 1962 as a high school football coach at three different schools including his alma mater, Grove City High School, and 1967 to 1975 as an assistant coach at Georgia Institute of Technology.  Bestwick was hired as the head football coach at Marshall University in 1971 after the 1970 plane crash that took the lives of most of the university's football team and coaching staff.  He left the position after two days on the job and returned to Georgia Tech.

Don Brown (American football coach): Don Brown (born July 31, 1955) is an American college football coach and former player.  He is currently the defensive coordinator at University of Michigan, a position he has held since December 2015.  Previously, he served as defensive coordinator Boston College and at the University of Connecticut and as the head football coach at Plymouth State University (1993–1995), Northeastern University (2000–2003), and the University of Massachusetts Amherst (2004–2008), compiling a career college football record of 95–45.  Brown was also the interim head baseball coach at Yale University in 1992, tallying a mark of 26–10.  on December 20th, 2015, he was hired as defensive coordinator at the University of Michigan.

John Gagliardi: John Gagliardi ( ; born November 1, 1926) is a former American football coach.  He was the head football coach at Saint John's University in Collegeville, Minnesota from 1953 until 2012.  From 1949 to 1952, he was the head football coach at Carroll College in Helena, Montana.  With a career record of 489–138–11, Gagliardi has the most wins of any coach in college football history.  His Saint John's Johnnies teams won four national titles: the NAIA National Football Championship in 1963 and 1965, and the NCAA Division III National Football Championship in 1976 and 2003.  Gagliardi was inducted into the College Football Hall of Fame in 2006.

Frank Beamer: Franklin Mitchell Beamer (born October 18, 1946) is a retired American college football coach, most notably for the Virginia Tech Hokies, and former college football player.  Beamer was a cornerback for Virginia Tech from 1966 to 1968.  His coaching experience began in 1972, and from 1981 to 1986 Beamer served as the head football coach at Murray State University.  He then went on to become the head football coach at Virginia Tech from 1987 until his final game in 2015.  He was one of the longest tenured active coaches in NCAA Division I FBS and, at the time of his retirement, was the winningest active coach at that level.  Beamer remains at Virginia Tech in the position of special assistant to the athletic director, where he focuses on athletic development and advancement.

Dennis Riccio: Dennis Riccio (born c. 1946) is a former American football player and coach.  He served as the head football coach at Frostburg State University in Frostburg, Maryland 1987 to 1991 and at St. Lawrence University in Canton, New York from 1992 to 1997, compiling a career college football record of 42–62.  Before his stint at Frostburg State, Riccio was the defensive coordinator at Augustana College in Rock Island, Illinois under head coach Bob Reade from 1983 to 1986, during which time the Augustana Vikings won four consecutive NCAA Division III National Football Championships. Ricco played college football at Illinois State University as a linebacker from 1964 to 1966.  Riccio also wrestled at Illinois State.  He moved to Augusta in 1979 to become head wrestling coach and assistant football coach.  He served as head wrestling coach there from 1979 to 1987, tallying a record of 63–56–3.

Bruce Chambers (American football): Bruce Chambers is an assistant athletic director at Arlington ISD and an American football coach.  He most recently served as an assistant to Charlie Strong at the University of Texas at Austin, and was the only member of the coaching staff retained from Mack Brown's staff.  Previously he served as coach at David W. Carter High School in Dallas, Texas.  After being dismissed from the staff on December 31, 2014, Chambers was hired by Arlington ISD as assistant athletic director.

Supporting paragraphs: Bruce Chambers (American football) Mack Brown
Answer: August 27, 1951