The 38 per cent cut was large enough to cause other government departments, Public Works and Industry Canada in particular, to sit up and take stock of the impact, internal documents obtained by The Canadian Press show.
One such document, a memo to Public Works Minister Diane Finley dated Feb. 5, 2014, indicates her department tried to convince defence officials to either abandon the cut or at least spread it out over a couple of years.
Defence officials said that would be impossible, because "they would not allow the department to meet its financial targets."
As a result, the 2014 ammunition budget was reduced to $94 million from $153 million.
During the early phases of the Afghan war, National Defence was caught similarly flat-footed and had to rush an order through General Dynamic Ordnance, particularly for artillery shells.
The memo surfaced on the same day Prime Minister Stephen Harper told the House of Commons that the cost of deploying special forces to northern Iraq is being taken out of the department's current budget.
Harper did not not say where the money would come from in any potential combat deployment, which was still being discussed behind closed doors on Wednesday. Nor would he speculate on how much a combat mission would cost.
"Our No. 1 priority is the safety and security of Canadians and the government will spend whatever is necessary to ensure that," Harper said during question period.
Opposition Leader Tom Mulcair accused the prime minister of dodging the question: "Is the prime minister really telling Canadians he has no idea — at all — how much it's going to cost? Ballpark? Nothing?"
During the 2006 election campaign, the Conservatives promised to fund overseas deployments separately from the hard-pressed defence budget.
The war in Afghanistan was given a special appropriation, but the Libya bombing campaign and the recently concluded Afghan training mission were not, according to briefing documents prepared for Defence Minister Rob Nicholson last year.
Both the NDP and Liberals clawed for details on Wednesday about the scope and size of the Harper government's commitment to the U.S.-led war against the militants known as the Islamic State of Iraq and the Levant.
A government motion detailing Canada's plans in Iraq, expected to include sending CF-18s on bombing runs, is expected in the coming days, likely on Friday.
The opposition parties won't say whether they'll support the motion until they see the details.
Conservative backbenchers were careful to stow any potential doubts following Wednesday's weekly caucus meeting.
"I think it's pretty safe to say we're united on this issue," said Alberta MP Laurie Hawn.
One bit of information that raised eyebrows was the revelation that the number of Canadian special forces soldiers advising Kurdish and Iraqi forces is much smaller than originally thought.
Foreign Affairs Minister John Baird confirmed that only 26 of the highly trained troops — not 69 as originally believed — are currently deployed in and around Irbil, in northern Iraq.
"The prime minister authorized up to 69 members of the Canadian Forces to provide training and assistance to stop the terrorist activities in Iraq," he told the Commons.
"We said, in fact, a few dozen, and we find that a few dozen are there."
The Conservative government, under repeated questioning in the House of Commons, revealed last month that up to 69 commandos were slated to deploy to help local forces battle ISIL.
A government official, speaking on condition of anonymity, said only a smaller contingent was required by allies, and noted that the 30-day deployment is under review.
The official, who was not authorized to discuss the matter publicly, said there were no problems getting the necessary diplomatic approvals, including an agreement setting out the limits of Canadian military involvement.
—With files from Jennifer Ditchburn
Follow @Murray_Brewster on Twitter
Also on HuffPost