The Prince of Wales complained to the then-prime minister Tony Blair about British forces in Iraq "being asked to do an extremely challenging job without the necessary resources", previously-secret letters have revealed.
In one letter, dated September 8, 2004, Charles speaks of problems with deploying new Oxbow surveillance technology, which he describes as a "major advance".
But he adds: "The aim of the Ministry of Defence and the Army Air Corps to deploy this equipment globally is, however, being frustrated by the poor performance of the existing Lynx aircraft in high temperatures.
"Despite this, the procurement of new aircraft to replace the Lynx (helicopter) is subject to further delays and uncertainty due to the significant pressure on the Defence Budget.
"I fear this is just one more example of where our Armed Forces are being asked to do an extremely challenging job (particularly in Iraq) without the necessary resources."
The letter to Mr Blair is one of 10 sent by the prince to ministers which have been released following a long legal battle.
A further 14 by ministers and three letters between private secretaries were also released following the long-running campaign by Guardian journalist Rob Evans to see the documents following a freedom of information request.
As the letters were released, Clarence House issued a statement defending the prince's correspondence with ministers,saying: "The publication of private letters can only inhibit his ability to express the concerns and suggestions which have been put to him in the course of his travels and meetings."
The statement also insists: "The Prince of Wales is raising issues of public concern, and trying to find practical ways to address the issues."
The statement said Charles carries out more than 600 engagements a year which "gives him a unique perspective" and has led to him identifying issues that "he, or his charities, or his other connections, can help address".
It went on: "Sometimes this leads him to communicate his experience or, indeed, his concerns or suggestions to ministers, from all Governments, of whatever party, either in meetings or in writing.
"Government ministers have often encouraged him to do so, and many have welcomed the Prince's views and ideas on a range of subjects. There are examples of this in the correspondence that has been made public."
In his response to the Lynx letter, Mr Blair replied on October 11 that year, saying that "limitations of the existing platform" were well known by the MOD, and the budget for the coming years included investment in helicopters.
He wrote: "While the Ministry of Defence clearly has to operate within finite resources, our planned investment in future helicopters will be substantial - £3 billion over the next ten years, and £6 billion over the coming two decades.
"Replacement of the Lynx and Gazelle reconnaissance and surveillance capabilities will be a priority for this programme which will seek to deliver a future fleet which is fully capable of deployment in all anticipated operational environments."
In one note to Mr Blair, the prince asks the prime minister to put "pressure" on the Department for Environment, Food and Rural Affairs over the bureaucratic burdens facing farmers.
Charles wrote in the lengthy letter dated September 8 2004: "Suffice it to say that any pressure which you can bring to bear on D.E.F.R.A. through the Panel for Regulatory Accountability, which you told me you are chairing, would be much appreciated.
"Vigilance is essential to help officials resist returning to type!"