One: The Beginnings
Europe had been relatively peaceful since the early part of the 19th century, interrupted only by some Prussian aggression during German unification (Thanks to ivan4 for the correction). After Napoleon, Europe had enjoyed a period of peace and prosperity. Significant developments during this time were the rise of a unified Germany (and Italy), and the (slight) weakening of the power of the ancient monarchic dynasties of Europe. Both Austria-Hungary and the Ottoman Empire experienced rebellion and a weakening of central government. These empires ruled over many ethnic groups and we know how much trouble that can cause. Austria's main problem were its Slavic states to the south.
Germany was unified by a brilliant man named Otto von Bismarck. Bismarck made a number of intelligent moves and succeeded in establishing an alliance with Austria-Hungary and Italy, known as the Triple Alliance. He also attempted to form an alliance with the Russian Empire and Austria-Hungary (The Three Emperor's League), in an effort to stave off an alliance between Germany's enemies France and Russia, but the league was not as much of a success as the Triple Alliance.
After Bismarck's dismissal a number of bad policy moves were made. Germany, which lay at the centre of Europe, had an advantage because, using its efficient railroads, it could swing its troops from one front to another quickly, and was at a disadvantage for the same reason--a combined attack on both fronts might squeeze it like a nutcracker. That was why Bismarck tried to stave off a Franco-Russian alliance, but his less wise successors did not succeed in this. France, since the Franco-Prussian war of 1870, had borne the Germans a grudge, both for the humiliation they (the French) suffered and for the capture of the border provinces of Alsace and Lorraine. Europe gradually split into two camps. One one side there were the Central Powers, Austria-Hungary, Germany and Italy. On the other side were Russia and France. Britain was not, strictly speaking, allied with France, but they had an entente (understanding). Russia also saw itself as the protector of all Slavic nations, including Serbia, which had previously been an Austro-Hungarian province but was now an independent nation.
By 1900 the stage was set for a war like Europe had never seen. A number of small conflicts in the decade from 1900 to 1910 nearly sent Europe spiralling into war but the affair blew over each time.
Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, was planning to tour Bosnia-Herzegovina, which was still an Austrian province. He favoured bringing Bosnia and the other Slavic states into the empire at the same level as Austria-Hungary. This made him popular with most of the people of Bosnia, but put him on the hit list of the Serbian radicals who favoured a Slavic state to the south. They were afraid that a moderate ruler would cause their platform to lose its appeal. One particular group of radicals, The Black Hand, decided to assassinate the Archduke.
During the Archduke's first drive through the streets of Sarajevo, a bomb was tossed into his car. Somehow, (reports are not conclusive) the bomb was ejected from the car, wounding several, but leaving Ferdinand unharmed. He was naturally not in the best of moods when he met Oskar Potiorek, Governor of Bosnia, but was informed that 'Bosnians never attempt assassination twice in one day'. After some time, the Archduke regained his composure, and he and his wife, Sophie von Chotkovato, left. The Archduke made a slight change of plans (driving down the Appel Quay to the Hospital), and the road that he was supposed to take was still unblocked, so the leading car in the motorcade turned, with the Archduke's car following. However, the error was pointed out, and the driver slowed and stopped. Before the driver could reverse, Gavrilo Princip, a member of the Black Hand, stepped out of the crowd and fired, shooting and killing Franz Ferdinand and his wife and setting Europe on the path to war.
Wow. Really melodramatic, eh?
Two: Austria and Serbia
As soon as Archduke Francis Ferdinand was assassinated, telegrams were dispatched all over Europe. Europe waited for the outcome, an outcome that could plunge Europe into the worst war the world had ever seen.
The Chief of Staff of the Austrian army, Conrad von Hotzendorff, advocated quickly sending the Austrian military into Serbia to teach the Serbs a lesson, despite the show of sympathy from Belgrade and a promise to crack down on terrorists. However, he was informed that his proposal was not feasable -- the Austrian military had to be mobilised (calling up reserves, starting a war economy, etc.) Moreover, the Austrian Foreign Minister, Count Leopold von Berchtold, advocated caution for many reasons, not the least of which were Russia's ties to Serbia. Russia had a huge army, but it was a paper army, as the war would soon show. All of Europe believed that Austria should deal harshly and quickly with Serbia... but how harshly? That was the question facing the Austrian government. And in a fateful move, they turned to their greatest ally, Germany, for help.
At this time, a representative of the German Foreign Office, Victor Naumann, basically gave Austria carte blanche. However, the German Ambassador, Heinrich von Tschirschky, advocated moderation. The Germans at this time were very sure of themselves. Germany had, indisputably, the greatest land army in Europe. With such a power backing them, it is no wonder that the Austrians did not excercise as much caution as they should have.
Finally, Austria decided to be firm. They prepared a careful ultimatum that demanded such outrageous concessions from Serbia that it was sure to be rejected by the Serbian government, thus giving the Austrians an excuse for war. At 18:00, July 23, 1914, the ultimatum was delivered by telegram, just hours after the French prime minister had left Russia. This was, of course, exactly what the hawkish Austrians (like Conrad) had planned.
Serbia was astonishingly submissive to Austrian demands. They only balked on the issue of having Serbian nationals tried by Austrian courts, which was a grave violation of international law. This was not, of course, what Conrad wanted. However, just to be sure, Serbia mobilised her troops on the 25th of July, ignoring the adage 'Mobilisation means war'. Hitting upon this as an excuse, Austria followed suit, with Brechtold getting the Emperor's signature by telling him that the Serbs were actually attacking. Meanwhile, the French prime minister was informed of the ultimatum aboard his ship. Russia, England and France started taking precautions for the coming war. At 11:00, July 28th, Austria declared war on Serbia, beginning The Great War of Europe, perhaps the most nationalistic war of all time and the first modern mechanised war. Over the next few days, July 30th to August 1st, Russia, France and Germany all mobilised.
Three: The Germans Attack
On July 31st, 1914, Germany issued an ultimatum to Russia (boy, this way seems full of ultimatums, doesn't it?). Desist or surrender. Germany demanded that Russia demobilise in 12 hours, or Germany would attack. After Russia's expected refusal, Germany mobilised and declared war on Russia on August 1st, 1914. The Germans had at first intended to strike Russia first, but they later decided to adopt the plan of Count Alfred von Schlieffen, Chief of the Great General Staff until 1906. The plan called for 10 divisions on the Eastern front and 8 attacking Verdun. Later, Helmuth von Moltke, Schlieffen's successor, modified the Schlieffen plan by strengthening the left wing. Contrary to many sources, Moltke did not significantly weaken the right wing. Stated very simply, the objective of the Schlieffen Plan was to crush France before Russia could mobilise, thus allowing the Germans to take their foes on one by one. An important modification of Moltke's was that Germany would now only violate the neutrality of Belgium (by Schlieffen's original plan, Germany would also have to invade the Netherlands). Many blame Moltke for Germany's defeat. Indeed, even Kaiser Wilhelm I (of Germany) became displeased with Moltke and replaced him with Erich von Falkenhayn later in the war.
Belgium mobilised on the same day as Germany. Germany attacked Luxembourg on August 2nd, and received neutral Belgium's declaration that they would not allow the the passage of German troops through Belgium. On August 4th, after Germany crossed the Meuse and invaded Belgium in accordance with the modified Schlieffen plan, Britain declared war on Germany and her ally, Austria-Hungary. Germany quickly managed to bring seven armies to bear on the western front and one on the eastern front (remember the Schlieffen Plan). However, all did not go as expected. Russia mobilised more quickly than anticipated and brought two armies to bear on the eastern front. On August 15th, Austria-Hungary finally invaded Serbia. Before that, on August 14th, the British Expeditionary Force, or BEF landed in France under the command of Sir John French. From the 22nd to the 25th, the French were driven back by the advancing Germans to the French fortified line east of Verdun. At Mons, the heavily outnumbered BEF was forced to retreat to the Marne (not to the ocean, as French Commander in Chief Joffre wanted them to do). Meanwhile, Joffre created the French Sixth Army, stationed in Paris. The Germans wheeled into France in a giant arc, the Second Army pausing momentarily at Guise.
The French Sixth Army, in Paris, attacked the advancing German First Army on September 5th. This began the Battle of the Marne (technically the first -- there were two others of the same name). The French were spared only by the arrival of reinforcements by Paris taxis. The German First Army dispatched two corps to meet the French attack, creating a division between the First and Second Armies. The French Fifth Army and the BEF moved into this gap, separating the two German armies. The German Command, afraid that they might lose the battle, ordered the retreat of the German First and Second Armies to the Aisne before they were cut off. The Marne dashed German hopes for a quick end to the war but did not seriously damage the German plan, as their retreat was successful. The war was about to be prolonged.
Four: The Eastern Front
The Goeben and the Breslau
The Goeben was Germany's greatest battle cruiser during World War I. It, along with a smaller ship, the Breslau were stationed in the Mediterranean under the command of Admiral Wilhelm Souchon. In August of 1913(*), the two ships began the attack of the coast of French Algiers. However, a few days later, he received a change of plan. His new assignment: To sail to the Ottoman Empire and convince the goverment to join the Central Powers. However, before Souchon had completed his assignment, the British battleships Indomitable and Indefatigable appeared on the scene. The Goeben and Breslau managed to outsail them, despite the Goeben experiencing engine trouble. The Germans landed in neutral Italy and were given a day to refuel. Meanwhile, the British, not entering Italian waters, blocked off the Germans' escape route. However, in doing so, they left the path to Constantinople wide open since they believed that the Germans would not sail into Ottoman harbours, not yet having been given permission to enter.
After the 24 hours were up, the Germans made a dash for it, heading towards Turkey. They were spotted by the British light cruiser, the Gloucester. Vice-Admiral Sir Archibald Berkeley Milne, in charge of the British fleet, was notified of this unforseen turn of events. The Gloucester pursued the Germans, but to no avail. However, while the Germans were passing Greece, four more British ships commanded by Admiral E. C. Troubridge took up the chase. While these ships were faster, the British decided that it would be impossible to get to the Goeben before that ship's superior artillery defeated them. The German ships, making it to Constantinople, gained entry and after negotiations, agreed to sell the Ottomans the Goeben and Breslau, now renamed the Yavuz Sultan Selim and the Midili, respectively. (Can anyone provide a translation for these?) Souchon now became the commander-in-chief of the Ottoman navy. Souchon's first act as an Ottoman soldier was to bomb the Russian cities of Odessa and Sebastopol. On October 30, 1914, Turkey became the third Central Power.
In August of 1914, General Alexander Samsonov became Commander of the Russian Second Army, in charge of the invasion of East Prussia. His initial attack against the German Eigth Army caused it to retreat and led to General Maximilian Prittwitz's dismissal. His replacements were General Paul von Hindenburg (of Hindenburg Line fame) and General Erich Ludendorff. On the 22nd they attacked the Russian Second Army at Tannenburg and in 7 days had it surrounded. After an unsuccessful retreat, Samsanov commited suicide. Only 10,000 of 150,000 Russian soldiers managed to escape.
The Brusilov Offensive
In April of 1916, General Aleksei A. Brusilov was made one of the three Russian Generals directly responsible to Tsar Nicholas II. He was given permission to begin an offensive to capture the strategically important Austro-Hungarian city of Kovel. The offensive involved four different armies, with the westward front launching the main attack. On June 4, 1916, the Russians attacked, breaking through the lines of the surprised Austro-Hungarians. After gaining several objectives, including capturing the city of Lutsk, the Russians were seized by a fit of anxiety and hesitated, thus losing the opportunity to capture Kovel. After a German counterattack, the Russians ended the offensive with much more territory than they had before, but still not having achieved their original aims.
More to come (maybe):
Part Five: The Gallipoli Campaign
Part Six: The War at Sea
Part Seven: The War in France
Part Eight: Verdun
Part Nine: Marne
Part Ten: The End for the Germans
Part Eleven: The Finale