World War I involved far more countries than most people realize. It began in 1914 as a local war between Austria-Hungary and Serbia. Before it was all over, it involved 32 countries. The majority of the fighting took place between the Central Powers (Austria-Hungary, Bulgaria, Germany and the Ottoman empire) against the Allied Powers (France, Great Britain, Italy, Russia and the United States).
World War I was the war of trenches, gas warfare and the introduction of airplanes and tanks used in battle. It also saw the construction of a line of fortifications by the Germans that stretched from North Sea south to Verdun, a length of approximately 200 miles.
Early in World War I, the Germans build defendable fortifications along the Western Front in France. They strategically chose high ground or ground in front of wet, marshy or boggy ground that would make crossing extremely difficult.
During the winter of 1916-17, they built a second defensive line closer to their own border. The Germans called this new defensive line the Siegfriedstellung (Siegfried Position) but the Allies referred to it as the Hindenburg Line. Running some 200 miles long, the Hindenburg Line was up to 12-15 kilometers (7.5 to 9.3 miles) deep.
The Hindenburg Line was built or divided into five zones, each named after figures from German mythology. Starting in the north from the North Sea, they were the Wotan, Siegfried, Alberich, Burnhild and Kriemhild.
The Germans build concrete and steel bunkers and other defendable structures in strategic locations and then stretched numerous rows of barbed wired between each structure. The Hindenburg line was built in such a way as to allow a rapid retreat of German troops if necessary but a very defendable line to repel enemy attacks.
On August 8, 1918, Allied forces launched their Hundred Days Offensive to drive the Germans behind the Hindenburg Line and to attack the southern section of the Line which the Allies believed to be the most vulnerable. Allied forces concentrated on the area where the Quentin Canal crossed through the Hindenburg Line. The Allied forces consisted of American, Australian, British, Canadian, French and New Zealand troops.
By the end of the summer of 1918, Allied forces had been successful in driving back the Germans along their Western Front.
By early September 1918, the bulk of the German forces along the Western Front had retreated back behind the Hindenburg Line, where they dug in, ready to defend their positions.
The Allied forces fought heavily along the Quentin canal, managing to advance about 500 yards every eight hours. There was heavy shelling from both sides. In the battle to capture the Quentin Canal, the British fired 945,052 artillery shells at the German positions and fortifications.
On this day, September 29, 1918, Allied forces, managed to break through the Hindenburg Line near Bellicourt. They used a carefully choreographed attack with aircraft, artillery, tanks and ground troops, all working together. The fighting was still hard and both sides suffered many casualties.
Fighting continued for four days with very heavy casualties on both sides. Eventually, the Allied forces forced the German forces into retreating further back, leaving them in a state of disarray. The breaching of the Hindenburg Line turned out to lead to the defeat of Germany later that year.
Sources for the above includes: The Hindenburg Line; Hindenburg Line; The German Retreat to the Hindenburg Line; Allied Forces Break Through the Hindenburg Line; The Battles of the Hindenburg Line; The Hindenburg Line: Breaking the Hindenburg Line; 1918-09-29: Breaking Through the Hindenburg Line; World War I