- April 26, 1915: Italy signs secret “London Pact”
- May 23: Italy declares war on Austria-Hungary
- February 21, 1916: Battle of Verdun begins
- July 1: Battle of the Somme begins
- August 18: Romania signs treaty with Allied Powers
- August 27: Romania declares war on Austria-Hungary, invades Transylvania
- September 1: Bulgaria declares war on Romania
- September 5: Bulgarian invasion of Romania reaches Danube just south of Bucharest
- November 18: Battles of Verdun, the Somme end
- June 7, 1917: Battle of Messines Ridge
- July 2: Greece declares war on Central Powers
- July 31: Battle of Passchendaele begins
- November 6: Canadian forces capture Passchendaele
Prior to the summer of 1914, Italy had been an ally of Germany and Austria-Hungary, as a member of the so-called Triple Alliance since 1882. When war broke out, however, Italy declared itself neutral and remained strictly so until the spring of 1915. All this time, Italy watched the war develop and calculated how to reap the greatest benefit from the situation.
The London Pact
In April 1915, Italy approached Austria-Hungary and offered its alliance to the Central Powers in exchange for a list of a half-dozen territories under Austrian control. When Austria refused a few days later, Italy turned to the Allied Powers with an even longer list of demands. Negotiations began immediately, and a few weeks later, on April 26, a secret agreement was signed that came to be known as the London Pact. The pact granted Italy claims to territories in Austria-Hungary, as well as in Albania, Turkey, and North Africa. Thus, on May 23, 1915, Italy declared war on Austria-Hungary.
South Tyrol and the Battle of Caporetto
Italian forces promptly advanced into the mountainous border regions of South Tyrol and to the Isonzo River. They made good progress at first, but within weeks, the front bogged down in the treacherous terrain, while the Austro-Hungarian forces pulled off a very effective defense. As a result, one more entrenched front line was added to the war.
The Italians and Austrians fought battle after battle along the Isonzo River, and though losses were huge, progress by either side was negligible. The situation continued largely unchanged until the Italians were defeated in the disastrous Battle Of Caporetto in October 1917 and forced to retreat from the area. A combined total of 750,000 casualties were lost on both sides during two and a half years of fighting in which nothing substantial was accomplished.
The Battle of Verdun
During the stalemate between Italy and Austria-Hungary, one of the longest and most catastrophic battles of the war was fought several hundred miles away, in France. On February 21, 1916, Germany launched an offensive against the fortified French town of Verdun, which guarded the approach to Paris. The Germans intended to make a sustained attack that would drain the enemy of soldiers and force a break in the stalemate. Both sides employed shells filled with Poison Gas on a large scale. France temporarily lost Verdun and its two forts but regained the forts by battle’s end and recaptured the town in a renewed attack that ended the battle on December 18. After ten months, the fighting ceased, with both sides back where they had started but with a staggering 650,000 soldiers dead. The Battle Of Verdun was the longest single battle of the war, and among the deadliest.
The Battle of the Somme
On July 1, 1916, even as the fight was still raging at Verdun, Allied Powers launched an offensive of their own along a twenty-five-mile front that extended across both banks of the River Somme. The opening artillery barrage was so heavy that it could be heard in southern England. During the four-and-a-half-month Battle Of The Somme, the Allies managed to make a small advance of only six miles, at a cost of 146,000 lives. The German death toll was 164,000.
The Stalemates in Europe
By 1916, all of the initial fronts of the war had reached stalemates, with both sides embedded in trenches and neither side gaining or losing much ground. All the while, soldiers were dying in massive numbers, simply for the sake of maintaining the status quo. The conflict was becoming a War Of Attrition, a gruesome contest to see which country could afford to lose the most soldiers. It was made all the more horrible by the fact that Britain, France, and Germany relied heavily upon their Colonies to bolster their supplies of fighting men. Of the major participants, only Russia and later the United States relied solely upon their own populations to fight the war.
Modern Weapons and the War of Attrition
The primary reason that World War I became a war of attrition was the use of Modern Weapons. Machine guns made it easy to cut down large numbers of men quickly if they came out into the open to fight. Once opposing armies became entrenched, long-range artillery, aerial bombs, and poison gas were used to try to force the other side to abandon its shelters and retreat.
Developments in Eastern Europe
While stalemates persisted in France and South Tyrol, the situation changed in eastern Europe, where several other nations joined the war. First was Romania, which had remained neutral for the first two years of the war but on August 18, 1916, signed a secret pact with the Allied Powers granting it the right to seize the territories of Transylvania, Bukovina, and Banat in exchange for entering the war on the Allied side. Shortly thereafter, on August 27, Romania declared war on Austria-Hungary and quickly moved forces across the border into Transylvania (then a part of Austria-Hungary).
The situation soon became more complicated when Bulgaria declared war on Romania on September 1. Bulgaria promptly followed up on its declaration: on September 5, Bulgarian forces, reinforced by German and Austrian troops, attacked the Romanians at the fortress of Tutracaia and succeeded in capturing 25,000 prisoners of war. The struggle continued for several months, but on December 6, 1916, German troops captured Bucharest.
Several months later, on June 27, 1917, Greece entered the war on the side of the Allied Powers, following the abdication of Greece’s pro-German king, Constantine I. Though Greece had been neutral through most of the war, it was surrounded by conflicts on all sides. While the king supported Germany, the government and a large portion of the population were sympathetic to the Allied Powers.
The Battle of Messines Ridge
Finally, in the summer of 1917, the British made the first small steps toward breaking the stalemate on the western front. At 3:10 a.m. on June 7, 1917, a series of simultaneous explosions ripped with amazing force through Messines Ridge in northern France—a fortified position along the front, where German forces had been entrenched for a long time. More than 10,000 German soldiers died instantly; those who survived were severely stunned and had no idea what had happened. Around them were craters of more than 400 feet in diameter. Before the Germans could regain their senses, the British army was upon them. Some 7,300 Germans were taken prisoner, while the rest retreated in shock.
For eighteen months prior, British soldiers had been digging a series of twenty-two tunnels below the German position. The tunnels extended up to 2,000 feet in length, and some were as far as 100 feet below the surface of the ridge where the Germans were dug in. Once complete, the tunnels were filled with 1 million pounds of high explosive and plugged with sandbags. The blast was heard as far away as London.
Slow British Progress in France
Although the Battle of Messines Ridge was a relatively small battle, it had considerable psychological impact for both sides. It also broke the Germans’ hold on the ridge, forcing them to retreat eastward and marking the beginning of a slow but continuous loss of ground by German forces in the west. After the battle, British forces continued to push the Germans back a few hundred yards at a time toward the high ridge at Passchendaele. The Germans fought back with Mustard Gas, a notoriously slow-acting chemical agent that maimed or killed enemy soldiers via severe blisters on the skin or internally if breathed.
The Battle of Passchendaele
By mid-September 1917, the British, close to their goal, began a new offensive movement. The fighting was slow and exhausting, and even the slightest forward progress came with innumerable casualties. The British reached Passchendaele on October 12 during a driving rain that turned the landscape to impenetrable mud. During the Battle Of Passchendaele that ensued, the British suffered 310,000 casualties, while German casualties numbered 260,000. The battle proved the last great battle of attrition on the western front and again saw the use of mustard gas and other deadly chemical weapons.