Newly released papers show the British government was deeply divided in private about the decision to try to re-take the Falkland Islands from Argentina in 1982.
The papers from the personal archive of the then prime minister Margaret Thatcher quote some senior members of the governing Conservative Party warning her that any conflict would be a serious mistake and that it might be advisable to let Argentina keep the islands.
The papers also show Mrs Thatcher's anxiety during the conflict and her conviction that Britain should not give in to a dictator.
A note from the whips' office following Argentina's 1982 invasion reported solid support for military action from some Conservative MPs, but others were privately hostile.
The papers have been published by Churchill College, Cambridge.
They show for the first time how deeply split the party was over the Falklands.
One Tory MP is quoted by the Whips as having said "we're making a big mistake, it'll make Suez look like common sense".
Another suggested letting Argentina have the Falklands with as little fuss as possible.
Others reportedly expressed hopes that "nobody thinks we are going to fight the Argentinians. We should blow up a few ships but nothing more".
The archive is her personal collection of what she thought worth keeping, and includes artefacts as well as documents and papers.
Rose to challenge
Among other new releases from the Falklands crisis are Mrs Thatcher's handwritten draft notes (including numerous crossings out) for her historic speech to the House of Commons on 3 April 1982, where she had to explain to MPs how the invasion had been allowed to happen.
There is also a copy of the Daily Mail, dating from just after the crisis broke, with a headline wondering whether "she had the stomach for it".
Speculating as to why she might have kept that particular newspaper, Lord Cecil Parkinson (who was a member of her war cabinet) told the BBC he was sure she was always aware she was being tested.
As Britain's first woman prime minister, he said, she would have known that people would be looking to see how she rose to the challenge of taking the country to war.
Other personal papers just released offer intriguing new insights into her state of mind at the time.
Notes on life at Number 10 showed that much of her day - and nights - were taken up with the war. A diary entry from one of her closest advisors, Sir Alan Walters, revealed she was up at 3:30 am, apparently waiting for front-line reports.
As the fight to take back the islands began in earnest, grim reports began to come through of ships being hit and the inevitable casualties. The archive includes the handwritten notes from duty clerks there were passed to her with the bad news.
She sometimes, apparently, could not control her grief. Her former aide Harvey Thomas remembers her breaking down in tears backstage at a constituency event on receiving the news that HMS Sheffield had been hit with an Exocet missile. It took her 40 minutes to pull herself together.
"She had received the news either immediately before she came or when she arrived," he told the BBC.
"She was deeply upset that she had to send British sailors to be killed and she was just quietly crying. Then somebody came in to the room and said: 'We have to get out there.'
"When she got back out on the platform she had pulled herself together, she was the prime minister, and she had a country to lead."
