Randy Duke, an ex-policeman, spent his annual leave, from working in Afghanistan, protesting against Cade Middle School in Victoria, Texas.
Duke's son Max was suspended from the for standing up to a bully who had picked on him for years, reports the Daily Mail.
In the latest incident, the unnamed bully stomped on a paper airplane that Max had given to a classmate with special needs. The bully then pushed Max, who pushed back, and a fight followed.
In response to the suspension of his son, Duke wore a sandwich board that read: 'BULLYING VICTIMS ARE PUNISHED HERE.'
Duke told KHOU-TV: "Max has been working hard to stay away from him, since he had been confronted by him and other kids before. They would use racial slurs, saying 'we don't like you because you're white.'"
The school suspended Max for two days, sent him to an alternative school for 30 days and kicked him out of the school's marching band.
Duke added: "[They] gave what I believe was a harsh punishment. They looked at this as a fight, which it was not. Had it been, in-school suspension would be an appropriate punishment."
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The school sent over police patrol cars to keep an eye on Duke's nonviolent protest and he knew all the officers.
Duke's wife Wendy eventually reached an agreement with the school in which the Dukes agreed to remove a formal complaint filed against the school, and the school agreed to re-enroll Max, who was able to perform with the marching band.
Duke, who will be returning to Afghanistan for another year, said he was able to watch his son perform in the band.