World War I battles often started with tactical objectives and devolved into bloody stalemates, but most historians believe that Verdun was intended to be a “meat grinder” from the very beginning. In late-1915, German General Erich von Falkenhayn wrote a memorandum to Kaiser Wilhelm II in which he argued that the war would only be won by inflicting mass casualties on the French army and sapping its will to fight, which would then force the British to sue for peace.

Rather than outmaneuvering them or breaking through their lines, Falkenhayn planned to lure the French into a trap that would force them to throw troops into a battle of attrition where the conditions favored the Germans. “If they do so,” he wrote in his memo, “the forces of France will bleed to death.” Falkenhayn called his ruthless scheme Operation Gericht—a term loosely translated as “judgment” or “place of execution.”

The Germans selected Verdun as their target not only because it was nestled in a salient, or bulge, in the Western Front, but also because it was steeped in political history. Verdun was an ancient city that had been among the last to fall during France’s humiliating defeat in the 1870-71’s Franco-Prussian War, and it had since been built into one of the most heavily fortified strongholds along the border with Germany.

Falkenhayn knew that any threat to it was likely to be fiercely contested since its fall would come as a serious blow to French morale. Interestingly, the city also had sentimental value for the Germans thanks to 843 A.D.’s Treaty of Verdun, which had divided the Carolingian Empire and created the core of what later became Germany.

Germany’s preparations for the Battle of Verdun involved one of World War I’s largest buildups of men and equipment. Using rugged terrain and a huge air presence to screen their movements, Falkenhayn’s men spent seven weeks constructing new railway lines, assembling heavy concrete bunkers to house troops, and stockpiling more than 1,200 artillery pieces.

A staggering 2.5 million shells were shipped to the front using 1,300 munitions trains. Despite the massive engineering project going on right under their noses, the French were largely unprepared for a German attack. The forts surrounding Verdun had seen little action during the early stages of the war, and many of their garrisons and artillery pieces had been moved to hotter sectors.

The French managed to make last-minute preparations after poor weather delayed the German onslaught, but they still found themselves on their back foot during the early stages of the battle. By February 24—just three days after the initial bombardment—the Germans had advanced several miles and overrun the first two French defensive lines.

On February 25, German forces approached Fort Douaumont, the most sprawling of the several dozen French bastions surrounding Verdun. Douaumont would have been all but impregnable under normal circumstances, but its garrison had been reduced to just 57 men in the months before the battle.

After gaining access to the fort through an undefended passage, a small party of Germans led by Lt. Eugen Radtke was able to wander its subterranean chambers and round up French defenders one after the other. They soon captured the entire garrison without suffering a single casualty or firing a shot.

News of Douaumont’s fall was met with impromptu celebrations and even a school holiday in Germany, but it came as a severe blow to the already wounded French morale. It would take eight months and tens of thousands of casualties before the French finally recaptured the fort in October 1916.

Due to a lack of secure railways and constant enemy bombardments, the French were forced to rely on a lone, 20-foot-wide road to supply their stand at Verdun. Upon taking command of French forces in late-February 1916, General Philippe Petain took steps to keep the lifeline open. Troops were put to work laying gravel and making repairs to the roadway, and a fleet of 3,000 military and civilian trucks was marshaled to serve as transport vehicles.

During just one week of operations, more than 190,000 French troops and 25,000 tons of munitions, food and supplies were ferried to the front. Petain also used the road to rotate more than 40 divisions in and out of the Verdun sector, which kept the French troops fresh and helped combat the effects of shell shock. The road was later renamed “La Voie Sacrée” (“the Sacred Way”) to commemorate its vital contribution to the war effort.

Of the 800,000 casualties at Verdun, an estimated 70 percent were caused by artillery. The Germans launched two million shells during their opening bombardment—more than in any engagement in history to that point—and the two sides eventually fired between 40 and 60 million shells over the next 10 months.

Rumbles from the barrages were heard as far as 100 miles away, and soldiers described certain hills as being so heavily bombed that they gushed fire like volcanoes. Those lucky enough to survive were often left with severe shell shock from the constant drumroll of falling bombs.

“I arrived there with 175 men,” wrote one Frenchman whose unit fell victim to a German artillery attack at Verdun. “I left with 34, several half mad…not replying anymore when I spoke to them.”

Germany seized command of the skies during the early stages of the Battle of Verdun, but the tables later turned after the French assembled a force of 226 planes and organized them into some of history’s first fighter squadrons. One of the most storied of these “escadrilles” was the Lafayette Squadron, an outfit composed largely of American pilots.

The unit was commissioned in April 1916—a year before the United States officially entered the war—and its roster eventually included 38 “Yankee” expatriates and veterans of the French Foreign Legion. The squadron won fame for the Indian brave emblems on its Nieuport fighters and a pair of lion cub mascots named “Whiskey” and “Soda,” but it also held its own in the air.

All told, Lafayette pilots chalked up some three-dozen aerial victories, most of them during five months of intermittent service at Verdun.

The Battle of the Somme is one of the few World War I engagements that matched Verdun for sheer bloodshed, but it may have relieved pressure on the French at a time when their forces were on the verge of collapse. Spurred on by French General Joseph Joffre’s pleas that his army would soon “cease to exist,” the Allies launched their costly assault at the Somme River on July 1, 1916.

Combined with Russia’s Brusilov Offensive, which led to the capture of hundreds of thousands of Austro-Hungarian troops on the Eastern Front, the attack forced the Germans to divert men and artillery away from the Verdun sector at a crucial juncture. The Germans continued attacking Verdun all the same, but following a failed final assault that July, they ceded the initiative to the French, who responded with a ferocious counterattack. By the time the battle finally sputtered out in late December, the French had regained their lost forts and effectively pushed the Germans back to where they started.

Ten months of shelling left the city of Verdun in shambles and resulted in the complete annihilation of the nearby towns of Beaumont, Bezonvaux, Cumières, Douaumont, Fleury, Haumont, Louvemont, Ornes, and Vaux.

The wealth of bodies and live shells in the ground ensured that these “villages détruits” (“destroyed villages”) were never rebuilt, but they still appear on French maps and are even administered by unelected volunteer mayors. Outside of a few scattered bits of rubble, all that remains of most of them today are signs that show where main roads and buildings were once located.

Despite the Germans’ plan to “bleed France white,” the Battle of Verdun resulted in roughly equal casualties for both sides. The German death toll was 143,000 (out of 337,000 total casualties) while the French lost 162,440 (out of 377,231).

Since artillery blasts buried many of the fallen or rendered their remains unidentifiable, most of the recovered bodies have since been placed in the Douaumont Ossuary, a sobering memorial that contains the mixed bones of at least 130,000 French and German soldiers.