In August, it will be a century since World War I broke out, a conflict that engulfed Europe and saw millions of servicemen sent to the front. In an era when even the telephone was not widely used, many soldiers turned to the picture postcard, then in its heyday, to send word home to loved ones.
Their parents, siblings and sweethearts replied in kind, leaving a treasure trove of images for present-day historians. Many that were produced and sent in wartime France are gathered in the Roger-Viollet Collection, represented here by Getty Images.
The postcards are real photographs, shot in black-and-white and hand-colored afterward, as color photography was in its infancy, said Sarah McDonald, a curator at Getty Images.
Publishers often used models in studio sets - in part for commercial reasons, since they were selling the images that people wanted to see, rather than accurate representations of the horrors of trench warfare. As a result, the equipment and uniforms portrayed in the studio shots are often inauthentic.
At the same time, the postcards and their "bons mots," or little messages, focus on emotional themes, such as patriotism, suffering, sacrifice, glory and romance, said McDonald.
While one might show a soldier with his sweetheart, with the slogan "My most tender kisses," another might praise a soldier's valor or depict an image of heroism on the battlefield.
"They unashamedly exploited sentimentality, which may seem naive and cloying to modern eyes, but which reflects the mood of the period," McDonald said.
"The soldiers sending these would want reassuring images for their family, rather than the grim reality of the front, and sweethearts at the front and at home wished to express their love and fidelity."
Like a present-day greetings card, the ready-written messages meant the sender need do little more than write the name and address of the recipient on the card's printed back, though there was space to write a longer missive too.
The printed message on one such postcard, showing a pensive woman with a pen in the foreground, with a soldier with bandaged head tended by a nurse in the background, reads, "I know you are injured and that makes me despair, dear victim of the ills of war."
The photographer's name only sometimes is featured on the card. One well-known studio outfit at the time was the Neurdein Brothers, which produced two of the images featured here.
These picture postcards were produced at the end of what is known as the "golden age" of picture postcards in France and elsewhere in Europe, extending from the turn of the century to World War I.
While telephones were not in wide use, postal delivery services were very good, allowing people to reach each other by mail relatively quickly - and advances in printing techniques helped to fuel a boom in picture postcards, in the United States as well as Europe.
When war broke out, British and German soldiers and their families would have exchanged such cards as well as the French, McDonald said, but the style differed according to the respective tastes in each country.
While the French postcards tend to be more sentimental or patriotic, the British equivalents are often comical and the German cards take a more aggressive tone, as does the country's propaganda material from the time, she said.
With their valiant portrayals of the war effort, the French picture postcards feed into the wider propaganda efforts of the time.
One shows French warships steaming across the sea, while another, depicting a black man incongruously wearing German "pickle" helmets, as they were known, appears to reference the French colonial empire. "Glory to the greatest France," the message reads.
The postcards also give an insight into the way that women were perceived or, at least, depicted, in the public sphere - and also what the postcard producers thought would sell to the women waiting at home.
Some of the cards show women working as nurses, appearing almost Madonna-like in their dress and angelic devotion, said McDonald. Other cards portray chaste women at home, thinking tenderly of a husband, father or brother at the front. A third type represents the woman as sweetheart or lover, perhaps saucily embracing a man or sending kisses.
The Roger-Viollet collection was amassed by Helene Roger-Viollet and her husband, Jean-Victor Fischer, both passionate photographers and travelers, who set up their agency in 1938. They bequeathed their huge selection of prints and negatives to the city of Paris.
Still collectable today, the World War I postcards represent "a fascinating social record for historians, despite the contrived studio settings and inauthentic costumes," said McDonald.
Laura Smith-Spark, CNN