Maj. Darryl Watts, 44, faces six charges, including manslaughter, in the death of Cpl. Josh Baker in February 2010.
Watts took the stand as his defence began at his court martial in Calgary on Monday.
He was the platoon commander at the firing range that day, but he told the military court that he had never been familiarized with the Claymore anti-personnel mine, also known as the C19, that the soldiers were using. He also testified that he had never been qualified to run a firing range and had informed his commanding officer of that.
He said it is common in the Canadian Forces to delegate tasks and Warrant Officer Paul Ravensdale was the range safety officer the day of the accident.
"I said 'I'm not qualified on the C19 but Warrant Ravensdale is,'" Watts testified. "Maj. Lunney agreed Warrant Ravensdale was qualified.
"It was Warrant Ravensdale's range. I had no concerns."
Baker, 24, died when the Claymore, packed with 700 steel balls, raked the Canadian Forces platoon on a range four kilometres north of Kandahar city. Baker was struck four times and one of the steel balls penetrated his chest.
Watts is charged with manslaughter, unlawfully causing bodily harm, breach of duty and negligent performance of duty.
The prosecution alleges Watts allowed his men to practise with the C19 without any proper training and with "wanton, reckless disregard.''
Watts said he didn't believe in "cutting corners" when it came to troop safety.
"Obviously the mission came first, but there was a way to mitigate the risks," he testified. "The safety of the soldiers was paramount."
Watts testified that everything seemed normal in the moments leading up to the deadly blast.
He said Ravensdale had given a detailed briefing before the first Claymore was fired without a hitch.
"I asked how it was going," said Watts of a conversation he had with Ravensdale.
"Warrant Ravensdale was content. It seemed normal to me."
Watts said he had searched for more detailed information on the C19 the night before the training exercise because he was "interested in how to set up the Claymore, how to unpackage it and fire it." But he couldn't get the training manual.
"I knew it had a small prohibited zone, had a very directional focus and the lethal zone was to the front."
Watts said he was getting a briefing on the C19 when the fatal accident occurred.
"The C19s fired, there was a pause and then I heard 'medic' being called. Where I was I had not seen the detonation."
He grew emotional as he recounted the details and briefly took a moment to have a drink of water.
Watts did say in an interview with military investigators after the blast that he felt responsible for the accident. But he told the court Monday that he meant he felt responsible from a moral perspective.
"As a platoon commander you have a moral responsibility to do anything in your power to ensure the safety of your platoon," he said.
Watts was the first witness to be called by his lawyer Balfour Der.
"By becoming a witness an accused person exposes themselves," Der said to the five-member panel that will determine Watts's guilt or innocence.
"Maj. Watts feels there's not a thing to hide."
Der said Watts had a lack of training on the Claymore and relied upon the "experience of Warrant Officer Ravensdale" to ensure the range was safe.
"This was a terrible accident and in hindsight it probably was preventable," said Der.
"But hindsight is not the lens by what we judge criminal intent."
Der said he intends to call one more witness before the defence wraps up his case.
Military prosecutor Maj. Dylan Kerr said he expected Watts would testify. He believes his inside knowledge will prove the prosecution's case.
"Certainly it's the prosecution's position that he was well prepared at the very least to supervise what was going on at that range," said Kerr.
Also on HuffPost