By December 1943, a group of 20 Saracen crewmen had covered around 60 miles from the Italian capital, reaching the area northwest of Cassino.

There Victor Crosby hid with an Italian family, waiting for an opportunity to slip across the front line. Before he could, one local reported him to the German authorities, who had occupied Italy after the September surrender.

Shot while trying to escape, he was subsequently executed by the German Army's police and buried in an unmarked grave near the village of Fontana Liri.

When the area was captured by the Allies the following spring, Crosby's body was dug up and reinterred at the new military cemetery at Cassino… but details of the submariner had been lost in the meantime, so he became an unknown sailor - the only Naval casualty of 4,000 casualties.

Nearly 75 years later, research by historians and the MOD's Joint Casualty and Compassionate Centre finally put a name to the anonymous headstone.

Victor Crosby's 83-year-old son made the pilgrimage to Cassino Commonwealth War Graves Cemetery for a service of rededication, led by Monsignor Andrew McFadden RN, Honorary Chaplain to The Queen and attended by serving submariners, UK Defence Attaché in Rome Cdr Neil Thompson and Italian villagers.

"I was only nine when Dad went, based at HMS Dolphin in Portsmouth he was involved in training and trials," said Mr Crosby.

"He went to sea in HMS Saracen initially for a trial and then we got a telegram saying 'Send submarine gear, shoving off'.

"It's been very emotional and brilliant to meet the current submariners - they've been fantastic. We will remember this for a long time; we have a grave now, which recognises my Dad's memory and his wartime service."

Author and historian Janet Dethick, who traced the fate of the crew after Saracen was lost, wanted to put a name to the unknown grave.

"Victor had been part of a group of 20 prisoners that had been in hiding, waiting to cross into the Allied lines," she explained. "I was determined to find out what had happened to all the crew and managed to gather the documents that proved where Victor was buried."