Today, 91-year-old Gautier and his friend Johannes Boerner, 88, are two of the dwindling number of veterans of the Allied D-Day landings and the ensuing nearly three-month battle of attrition that began to push German forces back from the western front of Nazi-occupied Europe.
Time and understanding have forged a bond between the former French elite commando and the German parachutist from Leipzig, who as neighbours in the Normandy town of Ouistreham celebrated Christmas together in 2012, and will both attend ceremonies next month marking the 70th anniversary of D-Day.
"We're like brothers now, it's just great for both of us," said Boerner, who took French citizenship in 1956 after marrying a local Norman woman.
It is one of the vagaries of history that both men live today in the same town where Gautier landed on D-Day, Tommy gun in hand and a year of training under his belt, one of Commander Philippe Kieffer's 177 French soldiers who battled the machine gun fire, landmines and barbed wire of Sword Beach as part of the No. 4 British Commando unit.
Besides the unforgettable sight of the armada of boats filling the sea, Gautier recalls rechecking his ammunition cartridge and his grenade just before landing, and how the photo of his wife Dorothea in his pocket got "a little wet".
"It was OK, though, I fixed it later," he said. "I still have it."
Shells from German bunkers rained down on Gautier and his commandos even before they reached land, but months of training and a surge of adrenaline outweighed their fear of the "Boches", the derogatory term used by the French for their enemy.
"Commander Kieffer had told us what would happen to us: 'It's possible that not even 10 of us will come out alive'."
The surprise amphibious attack – along with those by US, Canadian and British forces on the now-legendary beaches of Utah, Omaha, Gold and Juno – roused Boerner from his sleep far away in Brittany, setting him and the rest of the elite 2nd Fallschirmjaeger (parachute) unit on a 220-mile march to Normandy to shore up German defences and try to break the Allied bridgehead.
"The night of the 6th of June we were woken up with an alarm – 'The Allied troops are landing in Normandy!'," Boerner said. "We left for Saint-Lo, but we went on foot – 350km."
Gautier and Boerner were never in the same place at the same time in Normandy, but they retain kindred memories – the impenetrable hedgerows that snared tanks and hid snipers, hearing the voice of the enemy just metres away, the mosquitoes that infested the flooded valleys, the small green apples that were too sour to eat, and the smell of human corpses rotting in the heat.
Forced to evacuate Saint-Lo on July 17 with the approach of the Americans, Boerner and his German unit began a series of retreats to the interior, eventually finding themselves trapped in the "Cauldron", the Battle of the Falaise Pocket, encircled by Allied forces.
"The approach to Falaise was horrendous. They were all around us with their tanks, especially their planes, they just didn't let up," said Boerner. "There were bodies everywhere... there were 10,000 dead on the approach to Falaise."
Hungry, lice-ridden and demoralised, Boerner and his comrades from dispersed German units rifled the pockets of dead soldiers for cigarettes or food.
"We had nothing left. Our uniforms were dirty, in tatters... How were we going to get out of this?"
On August 21, after days of aerial and artillery bombardment, and unable to escape eastward through a narrow gap the Germans dubbed "the corridor of death", Boerner was taken prisoner by the Canadians.
He was one of the lucky ones – of Boerner's original company of 120 men, only nine survived.
"Falaise was one of the greatest killing grounds of the war," General Dwight Eisenhower later wrote in his memoirs. "It was literally possible to walk for hundreds of yards at a time, stepping on nothing but dead and decaying flesh."
For Boerner, prisoner of war camps and forced farm labour were his life until 1947. The Leipzig of his youth now in ruins and under Soviet control, Boerner decided that his new chapter would find him right where he already was – in Normandy.
Gautier was shipped back to Britain after three months of fighting in Normandy, one of only 25 French commandos to escape death or wounding in the Battle of Normandy.
Deployments in Britain, France and even Cameroon preceded a permanent move home to France for a career as a claims adjuster. After retirement, he moved to Ouistreham, and met Boerner at the latter's restaurant in the town, the "Chateaubriand".
A book about the two men, "Ennemis et frères" (Enemies and Brothers) by Jean-Charles Stasi, was published in 2010.
Boerner, his living room decorated with a cuckoo clock and beer steins, still has a full head of hair and the same gentle look that he had in his eye when he was photographed in his Luftwaffe uniform at the start of the war.
"I hope we never see another war like this because it's just not possible... The young men, the young men on the front there, shooting machine guns, it's just not possible. Freedom and peace, that's all I can tell you."
Gautier thinks about the flowers that he'll be laying on his fallen comrades' graves next month.
"For the young people – they need to know all about this," he said. "It cannot happen again. We have to be vigilant." – Reuters, May 13, 2014.