Gordon Brown staged a dramatic climbdown over cost-cutting plans to suspend routine training for the Territorial Army.
Labour MPs who criticised the £20 million cut in Parliament confirmed last night that Mr Brown had personally intervened to reverse the decision.
The move followed a series of conversations with Labour critics of the plan, including former Defence Secretary John Reid.
"I very much welcome the fact that the Prime Minister has been prepared to listen to the issues and personally intervene to make sure that the Territorial Army training budget is retained," Mr Reid said.
The disclosure of the latest retreat came as MPs prepared for a high-profile opposition day debate on the TA in the Commons today.
Under the cuts plan - part of a cost-cutting programme in the Army designed to save £54 million - the TA had faced the cancellation of all routine training for the rest of the financial year.
In the Commons on Monday, Armed Forces Minister Bill Rammell staged a partial climbdown, announcing a "small adjustment" of £2.5 million to allow TA soldiers to attend one drill night a month.
However, the concession failed to satisfy critics on all sides of the House, with a number of prominent figures on the Labour benches calling for a full re-think of the cuts plan.
Mr Reid confirmed that, after a series of conversations with Labour MPs, Mr Brown had agreed that the full budget should be reinstated.
"While there was never a threat to the training of those who were to be deployed in Afghanistan or other active posting, this reaffirmation of training for the whole of the Territorial Army will come as a great reassurance to the TA," he said.
"Gordon Brown and (Defence Secretary) Bob Ainsworth have always said that those who are taking the risks and making sacrifices would receive the back-up that they needed and I am delighted that they have confirmed that by their willingness to intervene in this."
Lindsay Hoyle, another Labour critic of the cuts, said he had directly asked Mr Brown to intervene in the dispute.
"I have already spoken to serving members of the Territorial Army, who are extremely pleased by this decision and I am sure it will be greatly welcomed throughout the armed forces who rely on the Territorial Army on frontline duties," he said.
"This decision will ensure that the one Army concept will remain."
Shadow defence minister Gerald Howarth said that the Government's climbdown was a victory for Tory leader David Cameron.
"David Cameron raised this issue at Prime Minister's Questions two weeks ago and we welcome this climbdown from Gordon Brown," he said.
"It is a shame that he and his ministers caused so much dismay to those loyal members of the TA training at home and putting their lives on the line in Afghanistan."
Liberal Democrat defence spokesman Nick Harvey said: "The state of the TA is much too important to be used as a political football in this way.
"It was a shocking error of judgment for the Government to have contemplated this cut in the first place.
"It is a sad fact that Gordon Brown's moral compass has only managed to kick in in the face of opposition across the board."
Shadow defence secretary Liam Fox said: "This episode has been a catastrophe for Labour who have again undermined the lack of understanding they have of our armed forces.
"Whilst it is another embarrassment for Gordon Brown, it is a victory for the forces of common sense, led by David Cameron and the Conservatives, which have saved the TA from what was a sad and humiliating policy decision."
There was "plenty of scope" to find savings through cutting waste elsewhere in the MOD, he said.Reuse content