This month marks the 70th anniversary of one of the most decisive battles of the Second World War. And the chief architect of Allied victory that day hailed from a Killyclogher.

This great battle in Italy will long stand out in history as one of the most famous episodes in this Second World War," wrote Winston Churchill to Field Marshal Sir Harold Alexander as ground and air forces under Alexander's command forced German armies in northern Italy to break asunder.

Churchill emphasised the "magnificently planned and executed operations" of the Allied 15th Army Group under the command of General Mark Clark. While Clark and President Truman acknowledged no contribution other than American in this final victory, Churchill was generous in his tribute to the many nations involved.

Of course, Churchill was aware of the polyglot nature of the Allied armies, especially Britain's Eighth Army, and mentioned the Poles, liberated Italians, New Zealanders, Indians and Jews who took part in the offensive. And there were also Brazilians under American command in the Fifth US Army.

Sadly, history so far has not recognised the campaign as Churchill thought it might.

Attention focused on northern Europe, where the Western Allies, having crossed the Rhine, were pushing the Germans back into the homeland, which was also being invaded by the Soviet Army from the east. Italy had been forgotten about.

But the only cohesive German armies, the 10th and the 14th, still fighting the Western Allies were in northern Italy. And at the beginning of April 1945, those armies were behind formidable defensive positions along a series of river lines.

To the west, their defences remained anchored in the Apennines, while to the east not only rivers, but the waters of Lake Comacchio, protected them.

As if that were not enough, they had deliberately flooded the land west of Comacchio to restrict attacking movement to a narrow strip near Argenta.

The German position was strong. Although lacking air power, they had sufficient troops to stave off any Allied attack. Or so they thought.

What Churchill called magnificent planning and execution was to be their downfall. And that planning and execution came not from Mark Clark, but from his two army commanders.

Lieutenant General Sir Richard McCreery was the Eighth Army's last commander. He was also its best, and the finest British field commander in Europe.

The Fifth Army was commanded by Lieutenant General Lucian King Truscott Jr, who had set up the US Rangers in Carrickfergus in 1942.

Both McCreery and Truscott were cavalrymen. That was not all they had in common. Both were of Irish descent. McCreery's family came from Killyclogher, near Omagh, from where his grandfather had emigrated to the USA in the 1860s, later coming back to settle in England. Truscott also had an Irish grandfather - and a Cornish grandmother.

The plans evolved to smash the German lines were their work. Operation Grapeshot was the army group plan, with the Eighth Army's Operation Buckland starting on April 9 and the Fifth Army's Operation Craftsman on April 14.

Hammered by heavy bombers and alternating strike-fighter attacks and artillery bombardments for hours, the Germans along the Senio river were then attacked by flame-thrower tanks as New Zealand, Polish and Indian troops assaulted their lines.

Carefully constructed and well-defended lines were breached quickly, and the New Zealanders raced for the even stronger Santerno river.

The Allies' speed had taken the Germans completely by surprise, and they didn't have enough time to man fully their Santerno defences.

As the Eighth Army swept forward, the Fifth Army prepared for its attack. One of its formations was the 34th Division, the Red Bulls, who had trained in Northern Ireland in 1942. But, as the Fifth Army was starting its attack, the British 78th Division in the Eighth Army was about to unleash its secret weapon: the Kangaroo Army.

The Kangaroo Army was built around a battalion of the Irish Brigade carried in Kangaroo armoured personnel carriers (APCs). These were Priest self-propelled guns with their weapons removed, or de-turreted Sherman tanks, able to carry a section of infantry.

Since the Kangaroos could move at the same pace as tanks, their "empouched" infantry could strike fast and hard.

The infantry in the Kangaroos were the 2nd London Irish Rifles, a TA battalion of the Royal Ulster Rifles and a unit with many native Irish in its ranks.

Commanded by the redoubtable "Bala" Bredin, the Irish Rifles were to lead the way to the Argenta Gap, where smashing through the German lines would allow the Eighth Army to advance to the River Po.

"Opening the door" for the Rifles were the other battalions of the Irish Brigade. True to their Gaelic motto "Faugh a Ballagh!" ("Clear the Way!"), the 1st Royal Irish Fusiliers did just that in co-operation with the 2nd Royal Inniskilling Fusiliers.

As the APC-borne Rifles surged ahead, the fusiliers fought hard to extend the Eighth Army's hold on the ground. Supported by tanks of the Bays, they kept the pressure on the enemy but suffered many casualties as they established a salient across a waterway. Among the Inniskillings' dead was Lieutenant George Murray from Belfast. The 27-year-old commanded a platoon in C Company under Major John Duane MC, a native of Co Galway.

Duane described how "George Murray with his platoon kept a steady stream of gunfire aimed at the other bank, as did his brother officer, Michael [Murray]. A great trust had developed between them. [On the morning of April 18] George put his head and shoulders over the mound. He was killed instantly by a sniper."

Both George and Michael Murray had already earned the Military Cross. Michael Murray was a native of Dublin.

The Germans had considered the route via Argenta impassable. Sir Richard McCreery thought otherwise. Flying over it in a spotter plane, he had decided that, rather than being an obstacle, the flooded ground could be a route for his advance.

While soldiers of the 56th (London) Division crossed the inundation in amphibious craft (Buffaloes), the 78th Division would secure Argenta town and the Eighth Army's armoured division would then lead the advance onwards to the Po. And so it worked out. There were difficulties - no plan works as it was intended - but these were overcome and the 56th Division, which included the 1st London Irish Rifles, had achieved its objectives. Meanwhile, the Kangaroo Army was en route to Argenta.

"Through the orchards ... in the narrow gap between Lake and Canal, moved a mass of armour, all passing over one bridge ... Wrecked vehicles, equipment and enemy dead strewed the route, whilst machine-gun fire, from an Argenta already surrounded, crackled away on the left flank."

With Argenta secure, the Eighth Army was able to race for the Po. Meanwhile, the Fifth Army, led by 10th Mountain Division, was also forging ahead.

In spite of their tenacity, the Germans were pushed back from river to river. New Zealanders reached Venice and then made for Trieste as 10th Mountain pushed towards Lake Garda.

But the Germans had had enough. On May 2, 1945, German forces in Italy and much of Austria surrendered to Field Marshal Alexander, three days before the surrender in Germany itself.

The best example of manoeuvre warfare by the Western Allies in Europe, Operation Grapeshot, deserves to be better remembered - as do the two army commanders, Richard McCreery and Lucian Truscott - not least because they were the best British and American generals in Europe.

Richard Doherty's Victory in Italy: 15th Army Group's Final Campaign 1945 is published by Pen & Sword Military (£25)