A major shakeup is in the offing amid the senior ranks of the Canadian military, one that appears to give the new chief of the defence staff an open field to implement the Harper government's long-planned defence reforms.

The country's deputy top commander, Vice-Admiral Bruce Donaldson, will retire in the coming months, along with the heads of the army and navy.

An internal notice posted late Tuesday at National Defence headquarters announced the changes, which come as the military struggles to deal with pending budget cuts and a massive internal reorganization.

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Vice-Adm. Donaldson will be replaced as vice-chief of defence staff by Lieutenant-General Guy Thibault, a career army officer who recently served in Washington.

The commander of the Canadian Army – Lt.-Gen. Peter Devlin, a veteran of Afghanistan – is also leaving, to be replaced by Lt.-Gen. J.M.M. Hainse, who currently serves as deputy commander of NATO's joint force command in Naples.

Lt.-Gen. Hainse will be replaced overseas by Major-General Jon Vance, the country's most experienced battlefield commander in Kandahar.

Vice-Adm. Paul Maddison, who only assumed command of the navy in July, 2011, also announced his retirement and will be replaced by Rear Admiral Mark Norman.

The changes of command, to be staggered over the next few months, follow the departure last fall of the longtime chief of defence staff, retired general Walt Natynczyk, and the former commander of the air force, retired lieutenant-general André DesChamps.

The latest changes mean that within the space of a few months the entire senior leadership of the military will have changed, said Douglas Bland, a defence analyst at Queen's University, in Kingston.

"I think a lot of people – myself and others on the outside – expected many of these officers were going to guide the Forces through the post-Afghan period," said Mr. Bland, the chair of the university's defence management studies program.

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Significant among the changes is the retirement of Maj.-Gen. Al Howard, who has been in charge of the defence renewal team. He'll be replaced by Rear Admiral Andrew Smith, the current chief of military personnel.

Mr. Bland said some officers were due to retire, but the clearing of the deck is significant at this point because some of those departing were apparently unhappy with the Harper government's transformation plans, as articulated in a report almost two years ago by another retired officer, former lieutenant-general Andrew Leslie.

It also comes ahead of what is expected to be a tough federal budget for the military.

"We'll see the disappearance of those people who resisted the transformations, that were reportedly well received in the prime minister's office," Mr. Bland said.

Mr. Leslie's watershed review of the military recommended drastic cuts to a bloated system of headquarters, private contractors, and the reserves.

While the report apparently won rave reviews with Prime Minister Stephen Harper and his chief of staff, it got a frosty reception from the defence establishment, which is interested in preserving the gains made during the Afghan war.

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The resistance culminated last June in the leaking of a letter from Mr. Harper to Defence Minister Peter MacKay that complained initial defence cuts did not go deep enough on the administrative side.

The message was reinforced last fall when Harper spoke at the change of command that saw Gen. Tom Lawson take over as chief of defence staff.

"The forces will also be subject to the same pressures that the uncertainties of the global economy have imposed across our government and around the world," Mr. Harper said.

"In order to free up resources to carry out work on the ground, administrative expenses have to be reduced."