During World War II, Van Heerden served as a gunner in North Africa, where he was taken prisoner at Benghazi along with another well-known Durban High School schoolmaster and rugby coach, Bill Payn.
He was a big, burly man, with a humorous, witty manner, a sharp temper, and a repertoire of ripe language which he used freely in both the classroom and on the rugby field.
Van Heerden's reputation as an innovative coach had spread to Argentina, and he was invited to Buenos Aires to help the Pumas prepare for their first visit to South Africa in 1965.
Izak van Heerden took leave from his teaching post in Durban, relocated to Argentina, learnt fluent Spanish, and would revolutionise Argentine play in the late 1960s, laying the way open for great players such as Hugo Porta.
The Pumas repaid the initial debt, by beating the Junior Springboks at Ellis Park, and emerged as one of the better modern rugby nations, thanks largely to the talents of this Durban schoolmaster.
Kitch Christie, who coached the Springboks for the 1995 Rugby World Cup, was quoted as saying Izak van Heerden "was truly light years ahead of the rest.
"[1] Tommy Bedford, who captained Natal and the Springboks in the 1960s, recalled that "Izak van Heerden was streets ahead of his time...We had a genius as a coach.
[2] More than half a century later, in 2015, twenty-four past and current Puma team members visited Durban High School to honor the coach who had transformed their game.