In World War I, facing the British sea blockade which resulted in the big famine in winter 1916/1917, softening the country's power of resistance, German naval warfare administration saw the sole solution in an illegal counter blockade via U-boat war. The sinking of the British ship "Lusitania" (containing tonnes of ammunition), killing 120 US citizens, lead to the ending of the U-boat war as well as to a strong tension between Germany and the USA. German military administration's optimism regarding the possibilty of finally overthrowing the British fleet resulted in a renewal of uncontrolled U-boat war on February 1, 1917 and caused the US declaration of war towards Germany. Thus, the superiority of the Allied forces was clear, World War I almost determined.
A peace resolution, demanding a "peace of consent and ronconciliation", passed German Reichstag, staying just as unsuccessful as a diplomatic initiative by pope Benedict XV.
Soon after this, weakened Russia agreed to the Treaty of Brest-Litovsk on February 9, 1918, for being able to concentrate on interior October Revolution. On the one hand, this made US president Wilson stress his 14 Points peace program. His most important matter of concern was the founding of a League of Nations, written down in point 14. Thus, the policy of power, dictated by national egoisms, should find an end. On the other hand, the peace of Brest-Litovsk was useful for reinforcing the German West Front, a major offensive being planned by general Ludendorff in spring 1918, thus further hardening the attitude of the Allies during Versailles.
In fact, August 8, 1918, the day of the battle of Amiens, became the "black day" for Germany. When Germany's allies collapsed, too, Ludendorff finally admitted defeat. On October 4, the German government asked for an armistice, basing on Wilson's 14 Points, and negotiations began. On November 11, the German delegation, leaded by Erzberger, signed the peace treaty of Compiègne, basing on the 14 Points. Thus, the peace of Brest-Litovsk was annulled, the sea blockade still valid; the political and military basis for a future freedom was set.
The attitude of The Big Three, negotiations concering Germany
On January 1919, the Paris Peace Conference, lead by Georges Clémenceau, started, heading towards creating a new order in territorially and politically smashed Europe, 32 nations taking part in total; Germany, Russia and the other defeated states were allowed to communicate with these via telegram. Major decisions were made by The Big Three, president Woodrow Wilson (USA), prime minister Georges Clémenceau (France) and prime minister Lloyd George (GB).
Wilson mostly aimed at creating a global peace order via a consentual peace, basing on his 14 Points and, as a major creditor of many West Allies, suggested a mild treatment of Germany, avoiding to ruin its economy for enabling it to pay reparations.
Lloyd George demanded a strong cutdown of German trade (handing over a big part of its trade fleet, annexation of all German colonies, but no major restrictions on the mainland), and, suffering from war debts, too, sufficient reparations. On the other hand, Germany was supposed to be reincluded in the association of states as well as isolated from Bolshevik Russia, creating a bulwark in Central Europe.
Clémenceau, though, not showing much intent to consent, pursued a policy of revanchism and security, particularly concerning territorial regulations (if possible, annexation of the Saar, separation of Rhineland, giving in to Poland’s wide-range territorial demands). Germany should never again become a hegemonial power in Europe. Thus, according to Clémenceau, peace should go hand in hand with creating French superiority on the continent, while banning Germany from the international society ("Germans have slaves' souls, the only argument they understand is violence" -Clémenceau).
Therefore, the actual treaty of peace was created as a compromise, highly disapproved of by German politicians such as Brockdorf-Rantzau, Secretary of State. Nevertheless, the Treaty of Versailles was, along with an ultimatum, handed over on June 16, 1919, followed by mass protests, particularly in Rhineland. Not long after this, the government under chancellor Philipp Scheidemann (SPD) resigned, unable to find any consent whether to sign or not. New chancellor Gustav Bauer (SPD) finally found a pro-signing majority, mostly for fear of endangering German unity as well as causing any harsher treatment than already written down in the treaty. Finally, Hermann Müller (Secretary of State, SPD) and Johannes Bell (Zentrum) signed the treaty on June, 28 in the Versailles Hall Of Mirrors, the same place the German Reich was proclaimed in 1871.
The Treaty of Versailles consisted of 15 parts, the first dealing with the founding of the Leage of Nations, although Germany itself was not supposed to join in, but non-members also had to follow the League's orders. (As said in a writeup by El Senor T before, the USA themselves refused to join in and, mostly therefore, never ratified the Treaty of Versailles and instead had their own peace treaty with Germany signed in August, 1921.)
Regarding territorial regulations, Germany was supposed to lose all rights concerning foreign countries and colonies, which from this point on were agreed to be administrated by the League of Nations. Alsace-Lorraine was to be handed over to France, Posen and West Prussia to Poland, "Hultschiner Ländchen" to Czechoslovakia, the Memel region to Luthuania, and Danzig was made a Free City.
The nationality of other European regions was to be decided via plebiscite, and thus Eupen-Malmedy handed over to Belgium, parts of Nordschleswig to Denmark, parts of East Prussia and Upper Silesia to Poland.
The Saar region was to be administrated by the League as well, the coal mines given to France, while a plebiscite, performed 15 years later, resulted in its staying German.
German land forces were to be reduced to 100.000, naval forces to 15.000, universal compulsory military service as well as several sorts of weapons were to be abolished, and a professional army created, observed by an Allies' commission.
The German Rhineland was demilitarized and divided into three parts which were supposed to be evacuated after 5, 10 and 15 years.
Concerning economical conditions, Germany’s status as a super power should be determined by taking most parts of its trade fleet, confiscation of German assets abroad, closing of export markets, and obligatory supply of the Allies with any kind of economical good.
As for war reparations, they should be handed over as gold, commodity, ships, bonds or otherwise to the value of 20 billions of Reichsmark until 1920, afterwards being replaced by long-term payments, thus meaning to force the German government to agree to signing a blank cheque.
The probably most debated articles, 227-231, also called War Guilt Clause, declared Germany and its allies as wholly and solely guilty of World War I, indicating emperor Wilhelm II as war criminal in article 227.
Ratification date was set January 1, 1920.
Results of the Treaty of Versailles
In Weimar Republic, this treaty was, especially because of the War Guilt Clause, regarded as "Schanddiktat" (meaning the Allies should be ashamed to force the German people into this), resulting in an increasing distrust between Germany and the West Allies, France's obvious resentments causing aggressions, which were, as the progressively politicalized war reparations issue, used by extreme rightists, later by the NSDAP, for their own purposes. Due to the general disapproval in public, Weimar Republic governments, leftist or rightist, from 1920 on ever tried to achieve revision, some way or the other.
As Germany was forbidden to join the League of Nations, and as the USA refused to join themselves, it was never estimated capable of encouraging and saving peace.
The territorial regulations resulted in many Germans living outside German borders, causing minority problems particularly in Czechoslovakia (Böhmen, Mähren, Sudetenland) and Poland (Upper Silesia).
Weimar Republic being isolated internationally just as Russia, they formed the Treaty of Rapallo on April 16, 1922, containing regulations about post-war payments, economical and military regulations, thus further complicating Germany's role in the West.
The war reparations, finally settled after the London Ultimatum of Mai 5, 1921, being 132 billions Reichsmark, 2 billions a year, plus 25 percent of all exports, burdened Weimar Republic's economy for a long time, causing 1923's Ruhrkampf, and weakening European economy as well.
Thus, German politics after the Treaty of Versailles oscillated between revisionism and fulfillment, causing national crises (e.g., fulfillment politician Matthias Erzberger was assassinated by a rightist in 1921) as well as international tensions, and, finally, after 1929's worldwide economic crisis, giving in to Hitler in 1933.
Informations taken from "Die Weimarer Republik, Band 1, 1919-1923", Bayerische Landeszentrale für politische Bildungsarbeit, Munich, Germany, 1994.
Thanks to eliserh!