Unknown “doughboys” parading in a village in France. The soldiers are not yet wearing their steel helmets, which indicates that they are newly arrived to France. (Courtesy Maine Military Historical Society)

Thursday marks the centennial of the U.S. entry into World War I. On April 6, 1917, Congress authorized then-President Woodrow Wilson’s declaration of war on Germany. The sinking of the ocean liner Lusitania in 1915, coupled with attacks on U.S. merchant ships and the Zimmerman Telegram in January, convinced a large swath of the American public that war was in the country’s interest.

Before official military involvement in World War I, Americans had contributed to the Allied war effort with participation in the American Field Service, which consisted of ambulance drivers and medical personnel. With the United States’ official entrance into the war, the American Field Service expanded its efforts, recruiting thousands more to serve overseas.

The first American combat troops arrived in France in June 1917. These soldiers were with the 1st U.S. Infantry Division and were accompanied by service members of the American Field Service. Once in France, the ambulance drivers and medical personnel were divided up into Section Sanitaire États-Unis, or S.S.U. for short. One of these men was an unnamed ambulance driver with S.S.U. 642 who took pictures of his experiences on the Western Front.

After the war, his photo scrapbook made its way to Maine, where it ended up with the papers and collections of Albert Greenlaw, an officer in the Maine National Guard and a World War I veteran himself. The scrapbook found its way into the Maine Military Historical Society’s museum in Augusta, Maine. These never-before seen photos provide a snapshot into the remarkable life of ambulance drivers in World War I.

Original caption: On Board the Espagne. A group of Poilus. The medals are the French Croix de Guerre.  “Poilu” was the affectionate term given by the French to their soldiers, much as the Americans referred to U.S. soldiers as “doughboys.” It is translated literally as “the hairy one.” Two of the poilu are wearing the Croix de Guerre, or cross of war, a French military medal for valor. (Courtesy Maine Military Historical Society)

Original caption: Cathedral of Rheims showing sandbags at foot and every window broken.  Completed at the end of the 13th century, the Cathedral at Reims was an important cultural, religious and political structure in France. It was targeted by German shells in 1914 during the early battles of World War I, destroying much of the structure. Angered at the destruction of an icon of their national heritage, the French used images of the battered cathedral in much of their war propaganda. (Courtesy Maine Military Historical Society)

Original caption: Two Boche roller kitchens destroyed by French shell of Neuville-Cauroy road. Four horses, three men, and two kitchens with one shell – Ambulance men examining wounds. Oct 9, 1918.  In addition to tending the wounds of French, American and British soldiers, ambulance personnel also did what they could for German wounded. (Courtesy Maine Military Historical Society)

Original caption: Band of the 118th Regt of the line, March 17, 1918. The 118th French Regiment of the Line was a veteran outfit with combat experience since 1914. It was nearly destroyed north of Reims in May 1918 after the Germans launched their massive spring offensive code-named Operation Michael. This offensive was a last-ditch effort to break the stalemate before the Americans could land troops in large numbers. After initial successes, the operation failed. (Courtesy Maine Military Historical Society)

Original caption: Christmas dinner in preparation, Juvigny, Dec. 23, 1917. The men of S.S.U. 642 spent their first Christmas in France in the small, war-torn village of Juvigny, near the French city of Soissons. American leadership in France made every effort to make the first Christmas for the American Expeditionary Force an enjoyable one, purchasing thousands of turkeys, pigs, sweet potatoes and other traditional Christmas food for the troops. (Courtesy Maine Military Historical Society)

Original caption: Murder! Ambulance men from S.S.U. 642 take advantage of some down time in the winter of 1917 to attend to hygiene standards. Short hair was important for the men of the American Expeditionary Force to fight the ever-present lice. (Courtesy Maine Military Historical Society)

Original caption: The spectators at a recent base ball game played ‘somewhere in France.’ Notice the French Poilus, the Canadians, the American ‘Sammies,’ and the one Hindu soldier. Sports of all kinds offered a welcome diversion to troops from every country. Baseball was made popular by American “Sammies” – the nickname given to U.S. troops because they served “Uncle Sam.” The British and French called upon all of their colonies and Commonwealth countries to assist them in the war, hence the presence of the Canadian and Indian soldiers. This was photo was taken circa 1918. (Courtesy Maine Military Historical Society)

Original caption: Refugees in the Somme. In spring of 1918, S.S.U. 642 was sent to support the British army fighting in the vicinity of the Somme, which had been the scene of horrific combat in 1916. French refugees from the German spring offensive of 1918 streamed through British lines. By September 1918, there were an estimated 1.85 million internally displaced persons in France. (Courtesy Maine Military Historical Society)

Original caption: Scene snapped during one the evacuations, the orderlies tend to getting the wounded out into the yard and then we take charge of them. The wounded are in two classes, the ones who have to lie down and those who can sit up. In the picture you can see the blesse’s [injured] on the ground and the men are preparing to lift into an ambulance. The Buicks are being loaded and the Panhards are drawn up in front of the picture. (Courtesy Maine Military Historical Society)

Original caption: Watching the American Troops march by the Obelisk in the Place de la Concorde on July 4th, 1917. The first American troops to parade through Paris was one battalion of the 16th U.S. Infantry Regiment on July 4, 1917. The parade culminated at the tomb of Marquis de Lafayette, the hero of the American Revolution. Col. Charles E. Stanton delivered a short speech, ending with the rousing words, “Lafayette, we are here!” (Courtesy Maine Military Historical Society)

Original caption: The American Contingent marching by the Magasins du Louvre on July 4th. For the French, who had endured years of war and enemy occupation, the arrival of the first American troops in June 1917 was a godsend. On July 4, 1917, a battalion of the 16th U.S. Infantry Regiment paraded through Paris — the first U.S. troops to enter the city. (Courtesy Maine Military Historical Society)