The newly released 'Palace letters' have revealed then governor-general Sir John Kerr sacked the Whitlam government in 1975 without giving advance notice to the Queen, because "it was better for Her Majesty not to know".
The 211 letters exchanged between Sir John and the palace at the time of the dismissal have this morning been released online by the National Archives of Australia, in Canberra.
The letters, penned between 1974 and 1977, had been locked up and labelled as private documents, but a High Court decision in May deemed them to be the property of the Commonwealth and thus able to be released.
Many hoped the correspondence would answer some of the long-standing questions surrounding Australia's biggest constitutional crisis.
But, due to interest in the letters, the National Archives' website is struggling to cope with the number of people trying to access it.
Sir John 'could not risk the outcome for the sake of the monarchy'
National Archives of Australia director-general David Fricker gave a brief overview of the correspondence ahead of the release.
He revealed that, in one letter, Sir John wrote that he had to act without giving prime minister Gough Whitlam a chance to call an election, because he feared he would be sacked himself, which would have put the Queen in a difficult position.
On November 20, 1975 - more than a week after the dismissal - Sir John wrote:
"As you know from earlier letters, on occasions, sometimes jocularly, sometimes less so, but on all occasions with what I considered to be underlying seriousness, he [Mr Whitlam] said that the crisis could end in a race to the Palace.
"I could act, if necessary, directly myself under the Constitution. I am sure that he would have known this and the talk about a race to the Palace really constituted another threat.
"History will doubtless provide an answer to this question, but I was in a position where, in my opinion, I simply could not risk the outcome for the sake of the monarchy.
"If, in the period of say 24 hours, during which he [Mr Whitlam] was considering his position, he advised the Queen in the strongest of terms that I should be immediately dismissed, the position would then have been that either I would, in fact, be trying to dismiss him while he was trying to dismiss me - an impossible position for the Queen."
The Queen's private secretary, Sir Martin Charteris responded:
"If I may say so with the greatest respect, I believe in not informing the Queen of what you intended to do before doing it, you acted not only with constitutional propriety, but also with admirable consideration for Her Majesty's position."
In the lead-up to the dismissal, Sir John and Sir Martin had discussed the evolving constitutional crisis - and in particular, what powers the governor-general had to intervene.
"Again, with great respect, I think you are playing the vice-regal hand with skill and wisdom," Sir Martin wrote on 4 November.
"Your interest in the situation has been demonstrated, and so has your impartiality.
"The fact you have powers is recognised. But it's also clear you will only use them in the last resort, and then only for constitutional - and not for political - reasons."
Other letters discuss constitutional amendments
Almost a year after the dismissal, on 21 September, 1976, in a handwritten letter from Sir John directly to the Queen, he wrote that there would "inevitably be discussion in Australia about constitutional amendment".
"But it will only be on the left wing, indeed on the far left that suggestions of fundamental change will be made," Sir John said.
"The great majority of Australians want it to remain as it is, with all its imperfections."
Altogether, the letters comprised 1200 pages and include press clippings about events in Australia at the time.
Fricker said his team at the National Archives had rushed to pore over the documents after the High Court ruled in late May they should be released.
He said the Archives would carefully consider the High Court judgment to decide whether any other royal correspondence in its collection would now be released.