An online petition condemning the Avon Maitland District School Board's decision had obtained more than 1,600 signatures as of early Monday afternoon.
The petition says Rick Boon, a teacher for the board, was denied permission to take his father, Art Boon, to an event commemorating the 70th anniversary of the liberation of Holland, after accompanying him to other ceremonies in previous years.
It says there is no other family member available or experienced enough to accompany the older Boon on the trip.
The school board, which administers public schools in Huron and Perth Counties, including the city of Stratford, says it considered a number of factors in making the call, including how many leaves the teacher had previously taken and what impact his absence would have on students.
The board says in a statement that the decision "was never intended as a slight" against the veteran or the "important role he has played both in serving our country and in preserving history for our students."
But many have condemned what they consider a disrespectful and unpatriotic move by administrators.
"I am appalled about the lack of respect that this shows for Mr. Boon and his son. Do you not have substitute teachers?" one wrote on the petition website.
"Mr. Boone has taught many generations respect for our armed forces and veterans. He is one on my son's personal heroes. His personal and professional conduct is deserving of any 'special' consideration that the school board should grant him," wrote another.
A woman who said she was one of Boon's past students and had heard his father speak at countless Remembrance Day assemblies called the board's decision "absurd."
"You really can't ask for a better learning experience for his students. Not only is this not just a regular leave of absence request but it is an amazing chance to bring history alive in Mr. Boon's classroom," she wrote on Facebook.
"I guarantee you that these students will learn far more from Rick and Art Boon about Canadian history and the war than they ever will from a text book. Please rethink your decision."
Boon's plight captured the attention of Loreena McKennitt, a Celtic musician and composer from Manitoba, who posted the petition.
"Art Boon senior was informally invited by the government of Friesland (a province in Holland) to attend this ceremony because the government wanted to, probably for the last time, honour any remaining vets for their contribution in the liberation," she said.
"I think many Canadians, not just people from Stratford...feel that he should be allowed to attend this with his son who has accompanied him on so many occasions and who is best equipped to accompany him."
The ceremony will take place from May 1 to 10.