The Holy Regiments were a military or paramilitary organization fighting on the planet Triannon. They were committed to the version of the local religion that said that the "Chosen Realm" was created in nine days, and opposed those who thought it was created in ten.
When he was a boy, D'Jamat fought with the Holy Regiment.
One of the missions that D'Jamat led with the Holy Regiment was to infiltrate a village known to be a heretic stronghold. They were seen by a six-year-old boy from the village. Knowing that if he returned to his camp they would be discovered, D'Jamat had the boy killed. He recounted this story to Captain Archer while the latter was deciding which of his crew would be killed by D'Jamat for desecrating one of the Spheres. (ENT: "Chosen Realm")