PARIS (AP) — A fallen soldier's letter from World War I that was discovered in France has touched authorities so much they launched a successful search for the soldier's living relatives.

The handwritten missive was written on May 27, 1915, from the Somme by 24-year-old Frenchman Sgt. Jean Soulagnes to a friend. Soulagnes was killed in fighting 12 days later in the battle of Hebuterne.

The letter was found by Marseille police in February in a search following a burglary.

With the aid of social media, authorities found Soulagnes' great-grandnephew, Stephane Drouhot. He attended a ceremony Frida...