Rear-Admiral Peter Dingemans: Naval officer who played a crucial role in the Falklands War as commander of HMS Intrepid

It was 20 May 1982. The Falkland Islands, shrouded in mist, lay ahead in the South Atlantic, and the old ship, with her scratch crew, shuddered to her captain's cry: "In a few hours, we must make war!"

That captain, Peter Dingemans, recalled, "I don't think that I have had a more unpleasant duty." He had both soldiers and sailors on board, many having been transferred from other ships on the journey from Portsmouth to be ready to use his vessel's vital attribute, her opening stern doors, with a flooded dock out of which landing craft bristling with troops could surge out to fight on a distant shore. But until that day, when last-ditch negotiations broke down, such a war had seemed the stuff of fantasy.

Dingemans was captain of HMS Intrepid, one of the two veteran 12,000-ton amphibious assault ships that made the retaking of the Falklands possible, after Argentina seized the islands on 2 April. The other ship was Captain Jeremy Larken's HMS Fearless. Both were under the command of Michael Clapp, Commodore Amphibious Warfare.

The two ships, each of which was known as a "Landing Platform, Dock" or LPD, had recently been written off by the Government under proposed cuts in defence spending, with no plans for replacements, so unlikely a prospect did overseas landings in anger appear.

Happily for red-faced planners in Whitehall, when the crisis broke, Dingemans had only just relinquished command of Intrepid, where he had run a tight ship with a crew versed in the elderly vessel's every quirk. Built in 1964, she was about to be decommissioned, her skilled company having been scattered to the winds. Only his speedy contacting of his trusty officers and men allowed the collection in short order of as near a crew to the original as could be done. Some came back from across the globe, others joined, and within a fortnight, on 15 April, under his renewed command, she sailed.

For Dingemans, a Sussex doctor's son, who in the 1950s served on Britain's last battleship, Vanguard, and in the 1970s intercepted marauding French and Russian vessels as Captain of Fishery Protection, the Falklands adventure was to impress on him more than any previous experience the true loneliness of leadership.

To prepare for the landings, rearrangements of men between ships – "cross-decking" – were necessary, and when on 19 May one of the transporting helicopters ditched and sank fast in the choppy sea, his swiftness in rescuing those who could be helped was praised. The incident, in which 22 died and eight saved, left the British Task Force saddened on the eve of battle.

"No one will speak… You will never be more alone in your life," Dingemans reflected, quoting the words of the Second World War Field Marshal Viscount "Bill" Slim. To have a commander's ruthless single-mindedness to see a task finished to the end, he felt, one needed faith in something much greater than oneself. He was to need every ounce of his faith in the following days, when Intrepid braved the stretch of water at San Carlos, from which the landings took place, that became known as "Bomb Alley" because of constant attack from the Argentinian air force.

On one occasion 75 enemy jets came over, 25 making at once for Intrepid. "Bombs were falling all around us but none hit," Dingemans remembered. "The air attacks came as no surprise but their ferocity did." To augment the ship's Sea Cat missiles he had placed machine guns and rifles manned by Royal Marines down both sides of the ship. His men's skill was equal even to one trick by the Argentinians, of a feint from one direction, with another Mirage aircraft suddenly appearing from the opposite side. "The Sea Cat aimer... had kept his eyes in the right place and fired just at the right time," he noted. The aircraft veered away, its bomb hastily ditched to no harm.

He also had luck: on another occasion, with bombs dropping, those below heard a clang against Intrepid's side; one had hit but failed to explode. Under cover of darkness Intrepid also made night trips to ferry men and materiel to creeks and inlets, and sent in a landing craft to act as a minesweeper, clearing channels using a piece of magnetised equipment so heavy that Intrepid's procedure of "docking down" in order to use it was fraught with danger.

Intrepid came under Exocet-guided missile attack when out at sea taking a Lynx helicopter to the Type 22 frigate HMS Brilliant, which was sailing with the main battle fleet led by the flagship aircraft carrier HMS Hermes: "Two Mirage jets came roaring in and fired two Exocet missiles at us", Dingemans recorded. "The first failed to acquire a target, the second was shot down ... we were just grateful that [someone] managed a bull's eye. "

She was also attacked half-way through the tricky manoeuvre of refuelling at sea, a process that could take many hours: "We got rid of the fuel lines and hoses attaching us, pronto."

During the journey south and during the war itself she notched up 4,750 "visitors" – including Commandos, Paratroopers, Scots Guards, SAS men and gunners – carried equipment from helicopters to bulldozers, held Argentinian prisoners, and even did much of the British forces' laundry.

For his crucial contribution to Britain's victory, Dingemans was awarded the DSO; he said the award was for the work of all his crew. The citation said: "Captain Dingemans took the closest personal charge of his ship's company, fought his ship magnificently, as well as providing every possible assistance to frigates, aircraft and landing ships. His example, energy and leadership were of the highest order."

Peter Dingemans, the eldest of five children, was educated at Brighton College and joined the Royal Navy in 1953. The name was Dutch; his grandfather, from the town of Zutphen, had become a naturalised Briton. His first command, in the mid-1960s, was the minesweeper HMS Maxton. He was promoted Captain in 1977.

After the Falklands war he became Commodore, Amphibious Warfare, Gibraltar, and then Chief of Staff to C-in-C Fleet at headquarters at Northwood, near London. On his retirement in the rank of Rear Admiral in 1990, he was appointed CB.

Peter George Valentin Dingemans, naval officer: born Steyning, West Sussex 31 July 1935; DSO 1982, CB 1990: married 1961 Faith Vivien Bristow (three sons); died Lindfield, West Sussex 6 December 2015.