In April 1917, British and French military leaders attacked in hopes of a decisive victory against Germany in La Vallée Foulon. This was a devastating example of how difficult victory could be in WWI. The campaign’s short-lived tactical successes came at considerable loss: in six weeks of fighting Allied forces sustained more than 187,000 casualties – a demoralizing toll which led to mutinies in the French Army.

Described by the U.S. Army in 1917 as "easily thickened; quick to build; easy to conceal; not easily destroyed," barbed wire had been in use since before WWI. Warring factions on all sides placed over 1 million miles of barbed wire between 1914 and 1918. Large amounts remain, embedded in farmland and forests across Europe.

The Battle of the Somme is considered one of the bloodiest in human history. On the opening day of the battle, July 1, 1916, the 1st Newfoundland Regiment attacked enemy lines. With their communication trenches blocked, they were unaware the units protecting their flanks were held down by artillery and machine gun fire. When the Newfoundlanders advanced "over the top" that morning, they were the only troops moving toward enemy positions by 9 a.m., exposed to artillery shells and bullets.

The months and years of fighting that followed July 1 left deep scars in the land around Beaumont Hamel, as seen in this aerial photograph, from artillery shells and intricate networks of trenches.

The British attacked German lines in the Battle of Messines (June 7-14, 1917), in hopes of regaining Ypres, Belgium. This reconstructed trench in Croonaert Wood – now a site of remembrance – demonstrates timber weaving as a technique for reinforcing trench walls and follows the exact layout of German trenches and positions.

When extending trenches through the Italian Alps, all forces faced two universal enemies: mountains and weather. Armies learned new alpine climbing techniques to move soldiers and equipment through mountains. Winter temperatures dipped well below freezing and snow fell in summer, making it hard to keep soldiers supplied: a single mountaintop garrison of 100 people required over 900 porters. Over the three years of fighting on the Dolomite front, almost 90,000 soldiers died, with two-thirds of those deaths caused by natural disasters like lightning, blizzards, avalanches and rockfalls.

Author J.R.R. Tolkien served as a Signals Officer between June and Nov. 1916 in the marshlands along the Ancre River in the Somme. It is believed they were the inspiration for the Dead Marshes in Tolkien's "Lord of the Rings" trilogy.

Located near Woinville and built by a German construction and cement unit, this bunker provided ammunition storage for the German artillery batteries along the Woëvre plain. Despite the ever-expanding building and repair requirements across the Western Front, many German construction projects continued to include unique design qualities and beautiful craftsmanship in their work.

Built by a German Pioneer unit from the Bavarian II Army Corps, the Quatre Goulots is one of several spring-fed wells designed and ornamented by German construction units on the Western Front. These sites served as wash stations and rest spots not far from the front lines, but far enough to provide respite from the fighting.

Soldiers often left permanent reminders of their fleeting presence throughout WWI. A unique set of carvings from French, British and German units sit next to each other in a French quarry. Between Sept. 1914 and Jan. 1915, the Royal Hampshires, the French 45th Chasseurs à Pied and a Prussian Grenadier Regiment would each occupy the same terrain and leave their unit insignias beside each other.

The hill at Montsec has a commanding view of the Meuse countryside. This was the site of the St. Mihiel Salient, a fierce battle between Germans, French and Americans in Sept. 1918. Finally captured by American forces on Sept. 12, the hill was concealed under an intense smokescreen that allowed the Allies to surround the German defenses and force their surrender.