Charles Kuentz was born on February 18, 1897 in the village of Ranspach in Alsace, then part of the German empire under Kaiser Wilhelm II.
Conscripted into the imperial army in 1916, he found himself on the losing side when the first World War ended in 1918 but soon afterwards became a French citizen when France recovered Alsace, a territory it had lost after a previous war, in 1871.
"I thought I was the last World War I German veteran, that's what the German reporters told me," Kuentz told AFP in an interview, but conceded that he might be only one of a few survivors.
After World War II broke out, Kuentz was again called up, this time by the French army in 1940.
He was soon demobilised, because of his age and family responsibilities, and went to live in the city of Colmar, which reverted to Germany when Adolf Hitler's army occupied France and again annexed Alsace and its twin province of Lorraine until its defeat in May 1945.
"My father, who died at the age of 92, changed nationalities five times and I did four times," said Kuentz.
He showed no bitterness, even though his eldest son died in 1944, wearing the uniform of Hitler's Waffen SS which he, like other Alsatians, had been forced to don.
Today, Kuentz still lives in Colmar, close to his son and daughter, aged 70 and 74.
Speaking alternately in French, German and Alsatian, he said he did not often reflect upon his wartime experiences, but he recalled the bitter cold on the eastern front in Russia, where temperatures fell to minus 40 degrees Celsius (minus 40 Fahrenheit).
There, as in Flanders and in the Champagne region, east of Paris, where a final German offensive was broken by the US Army, he remembers the soaking uniforms, the rats and the ever-present fear of death.
The Germans mistrusted the Alsatians and refused to grant them leave, fearing that they would desert, and Kuentz believes that his life was saved when he stood up to a German captain.
"I told him that I would not go back to the front," he said. "The next day I was allowed to take a few days' leave and during that time my regiment suffered heavy losses."
At 107, Kuentz has some problems with his hearing and walks with difficulty, but he eats well, reads the newspapers regularly and attributes his long life to "doing everything in moderation."
He has given about 30 interviews in recent months but, while he admits to being a little tired, he stresses that he has "a duty to bear witness" for future generations.
"Pass on the memory of the Great War, because this tragedy must never be forgotten, otherwise it will happen again," he said.