Neglected for decades, underground caves in a small village in France's Somme valley contain a treasure trove of hundreds of engravings by World War I Canadian and British soldiers as they sought refuge from German assaults.
Most of the inscriptions date back to 1916, many from July of that year when the Battle of the Somme started.
Nearly 20,000 British soldiers were killed on the first day; by the battle's end in mid-November, the two sides had together suffered over a million casualties.
War researchers say the engravings in the chalky rocks of Bouzincourt offer a powerful insight into the thoughts of those caught up in the Somme Offensive, one of the bloodiest battles in world history.
Check them out below.