Without Captain Astiz, there'd have been no such thing as Thatcherism

This week Britain celebrates the feast of the empty gesture. Millions who had nothing to do with slavery will pretend to apologise for it, largely because the BBC has gone potty. Tony Blair will presumably find a black person and say: "I feel your pain."

Meanwhile, there is a more recent anniversary to commemorate, 25 years since the Falklands war. Should we apologise for that?

Last week, an Italian court eerily brought the Falklands war full circle. Alfredo Astiz, a former Argentinian navy captain, was convicted in his absence of the sadistic murder of three Italian students in the 1970s. He is also wanted for the deaths of two French nuns and a Swede, not to mention thousands of Argentinians. An arch-practitioner of Argentina's "dirty war", Astiz had been protected by successive Buenos Aires presidents, until the current one, Néstor Kirchner, himself a dirty-war victim. Extradition is now under way.

Astiz is one of those characters on whom historic causality can suddenly seem to spin. He caused the Falklands war. Were it not for him, the original Argentinian plan to invade the islands would have succeeded. The Argentinian dictator, Galtieri, would have triumphed, and Margaret Thatcher would have resigned or been defeated at the polls. Old Labour would have returned to power. There would have been no Thatcherism, no British revival, no Tony Blair, no Gordon Brown.

In the autumn of 1981 the Argentinian navy was worrying about its image: valiant not at seamanship but at hoods, clubs, electrodes, rapes, beatings and droppings from planes. Astiz was chief ghoul in the naval mechanical school, and his superiors were keen to cleanse his and their reputation. The head of the navy, Admiral Jorge Anaya, a small, chippy Bolivian, had developed a hatred for the British after a lonely spell as naval attache in the Vauxhall Bridge Road. He and his colleagues discussed celebrating a coup in 1981 by seizing South Georgia, as they had Thule, in the South Sandwich Islands, in 1976.

Intelligence indicated dwindling British interest in the south Atlantic, notably the withdrawal of HMS Endurance and the denial of full British citizenship to the Falkland islanders. It was planned that Astiz would accompany an expedition to clear British scrap from South Georgia when Endurance left in March. They would sit out the winter and eventually raise the Argentinian flag.

Then in December 1981 Anaya secured a bolder decision from the new president, General Galtieri - to seize the main Falkland Islands. The plan, prepared by Anaya's colleague, Admiral Lombardo, would be activated between May and July 1982. There would be no bloodshed, no inflow of colonists, just the removal of the governor and an exchange of garrison, pending negotiations through the United Nations. It would be "coercive diplomacy". India's peaceful seizure of Goa in 1961 was much cited as precedent.

Lombardo specifically told Anaya to cancel Astiz's South Georgia operation, planned for March, for fear of alerting the British and possibly pre-empting the main invasion, planned for no earlier than May 15. Anaya agreed, but did not do so. He apparently dared not disappoint Astiz and his colleagues, whose antics had made them feared more than admired in naval circles. South Georgia went ahead, and with maximum bravado.

This double-crossing of Lombardo held the key to all that followed. Lombardo was on holiday in Uruguay when he read that Astiz, under cover of the scrap merchants, had landed on South Georgia on March 24. Racing home to challenge Anaya, he was told simply to bring forward the invasion plan at once. Anaya was now terrified of British submarines, and warned the junta that if they appeared round the Falklands the navy would have to return to port.

As it was, none of Lombardo's units was in place, and Anaya told him to use any troops or ships available. The seizure must be a fait accompli before the British could react or the world notice what had happened. That a tri-service invasion took place a week later, on April 2, was a tribute to Lombardo's skill. It was indeed swift and bloodless, though with no time or thought given to winning "hearts and minds".

The rest is history. Astiz did indeed alert the British and pre-empt Lombardo's plan for a winter invasion. Endurance was still in Falklands waters and a submarine still in Gibraltar and available to sail south. Sending a task force south in April was just feasible, albeit against the run of professional advice. Once sent, politics forbade its recall even as the cost (and risk) of recapturing the islands soared. When the Belgrano was sunk, the Argentinian fleet fled to harbour, as Anaya said it would, and Argentina lost what had been an overwhelming tactical superiority.

With the islands a casus belli, America had to come off the fence and support Britain, though privately. With soldiers and sailors dying by the hundred, Thatcher dared not negotiate or compromise. When she eventually won, she was transformed from a hated factionalist to a global heroine. With the Social Democrats ascendant in early 1981 and Thatcher deeply unpopular, it was near inconceivable that she would have survived as a majority prime minister beyond her first term.

Instead she and her party gained 10 percentage points and never lost them. The "golden age" of Thatcherism followed, with three more Tory election victories and a parallel revolution in Labour policy under Tony Blair. The Falklands victory reinvigorated Britain and spurred Thatcher to press on with overdue industrial reform. It at last allowed a British government to implement a coherent programme and an opposition not to reverse it. In Argentina the Falklands ended the dirty war and bundled the drunken Galtieri from office, leading to a hesitant democracy.

Should anyone apologise for the Falklands war? If it makes any difference, yes, the Argentinians. Was it a legal war? Yes. Thatcher, unlike Blair, was scrupulous in covering her legal flank. Was it a just war? Yes again. Force should not be used to seize people or territory against their will, and may indeed be resisted by force (as after Saddam's invasion of Kuwait).

But was it all worth it? That is a different question. War should deter but seldom does. Just as Britain's Trident did not deter Galtieri, so his defeat did not deter Saddam or Assad or Mengistu or any other dictator minded to take a pot shot at a neighbour. Thatcher expended 255 British lives and £3bn indulging the intransigence of a thousand islanders, shortly after ditching the equally British Diego Garcians for a pot of American gold. Nor will the Falklanders ever be safe while they pretend to be offshore Hampshire rather than Argentina.

The Falklands was a classic Hamlet war. There was no great argument, rather a leader "greatly to find quarrel in a straw when honour's at the stake". Such wars cannot be weighed against their immediate cost: they are never worth it. But seen in the warp and weft of 20th-century history I still regard the Falklands war as in credit, and for that we can thank the treachery and bombast of Admiral Anaya and Captain Astiz. May their podium be a prison cell.

Simon Jenkins