Central Powers

German soldiers in the battlefield in August 1914 on the Western Front shortly after the outbreak of war

German cavalry entering Warsaw in 1915

German battlecruiser SMS Seydlitz heavily damaged after the Battle of Jutland

German Fokker Dr.I fighter aircraft of Jasta 26 at Erchin in German-occupied territory of France

In early July 1914, in the aftermath of the assassination of Austro-Hungarian Archduke Franz Ferdinand and the immediate likelihood of war between Austria-Hungary and Serbia, Kaiser Wilhelm II and the German government informed the Austro-Hungarian government that Germany would uphold its alliance with Austria-Hungary and defend it from possible Russian intervention if a war between Austria-Hungary and Serbia took place.[6] When Russia enacted a general mobilization, Germany viewed the act as provocative.[7] The Russian government promised Germany that its general mobilization did not mean preparation for war with Germany but was a reaction to the events between Austria-Hungary and Serbia.[7] The German government regarded the Russian promise of no war with Germany to be nonsense in light of its general mobilization, and Germany, in turn, mobilized for war.[7] On 1 August, Germany sent an ultimatum to Russia stating that since both Germany and Russia were in a state of military mobilization, an effective state of war existed between the two countries.[8] Later that day, France, an ally of Russia, declared a state of general mobilization.[8]

In August 1914, Germany waged war on Russia, citing Russian aggression as demonstrated by the mobilization of the Russian army, which had resulted in Germany mobilizing in response.[9]

After Germany declared war on Russia, France with its alliance with Russia prepared a general mobilization in expectation of war. On 3 August 1914, Germany responded to this action by declaring war on France.[10] Germany, facing a two-front war, enacted what was known as the Schlieffen Plan, that involved German armed forces needing to move through Belgium and swing south into France and towards the French capital of Paris. This plan was hoped to quickly gain victory against the French and allow German forces to concentrate on the Eastern Front. Belgium was a neutral country and would not accept German forces crossing its territory. Germany disregarded Belgian neutrality and invaded the country to launch an offensive towards Paris. This caused Great Britain to declare war against the German Empire, as the action violated the Treaty of London that both nations signed in 1839 guaranteeing Belgian neutrality and defense of the kingdom if a nation reneged.

Subsequently, several states declared war on Germany in late August 1914, with Italy declaring war on Austria-Hungary in 1915 and Germany on 27 August 1916, the United States declaring war on Germany on 6 April 1917 and Greece declaring war on Germany in July 1917.

Europe

Upon its founding in 1871, the German Empire controlled Alsace-Lorraine as an "imperial territory" incorporated from France after the Franco-Prussian War. It was held as part of Germany's sovereign territory.

Africa

Germany held multiple African colonies at the time of World War I. All of Germany's African colonies were invaded and occupied by Allied forces during the war.

Kamerun, German East Africa, and German Southwest Africa were German colonies in Africa. Togoland was a German protectorate in Africa.

Asia

The Kiautschou Bay concession was a German dependency in East Asia leased from China in 1898. It was occupied by Japanese forces following the Siege of Tsingtao.

Pacific

German New Guinea was a German protectorate in the Pacific. It was occupied by Australian forces in 1914.

German Samoa was a German protectorate following the Tripartite Convention. It was occupied by the New Zealand Expeditionary Force in 1914.

Austria-Hungary regarded the assassination of Archduke Franz Ferdinand as being orchestrated with the assistance of Serbia.[6] The country viewed the assassination as setting a dangerous precedent of encouraging the country's South Slav population to rebel and threaten to tear apart the multinational country.[7] Austria-Hungary formally sent an ultimatum to Serbia demanding a full-scale investigation of Serbian government complicity in the assassination, and complete compliance by Serbia in agreeing to the terms demanded by Austria-Hungary.[6] Serbia submitted to accept most of the demands. However, Austria-Hungary viewed this as insufficient and used this lack of full compliance to justify military intervention.[11] These demands have been viewed as a diplomatic cover for what was going to be an inevitable Austro-Hungarian declaration of war on Serbia.[11]

Austria-Hungary had been warned by Russia that the Russian government would not tolerate Austria-Hungary invading Serbia.[11] However, with Germany supporting Austria-Hungary's actions, the Austro-Hungarian government hoped that Russia would not intervene and that the conflict with Serbia would be a regional conflict.[6]

Austria-Hungary's invasion of Serbia resulted in Russia declaring war on the country and Germany in turn declared war on Russia, setting off the beginning of the clash of alliances that resulted in the World War.

Territory

Austria-Hungary was internally divided into two states with their own governments, joined in communion through the Habsburg throne. Austrian Cisleithania contained various duchies and principalities but also the Kingdom of Bohemia, the Kingdom of Dalmatia, the Kingdom of Galicia and Lodomeria. Hungarian Transleithania comprised the Kingdom of Hungary and the Kingdom of Croatia-Slavonia. In Bosnia and Herzegovina sovereign authority was shared by both Austria and Hungary.

The Ottoman Empire joined the war on the side of the Central Powers in November 1914. The Ottoman Empire had gained strong economic connections with Germany through the Berlin-to-Baghdad railway project that was still incomplete at the time.[12] The Ottoman Empire made a formal alliance with Germany signed on 2 August 1914.[13] The alliance treaty expected that the Ottoman Empire would become involved in the conflict in a short amount of time.[13] However, for the first several months of the war the Ottoman Empire maintained neutrality though it allowed a German naval squadron to enter and stay near the strait of Bosphorus.[14] Ottoman officials informed the German government that the country needed time to prepare for conflict.[14] Germany provided financial aid and weapons shipments to the Ottoman Empire.[13]

After pressure escalated from the German government demanding that the Ottoman Empire fulfill its treaty obligations, or else Germany would expel the country from the alliance and terminate economic and military assistance, the Ottoman government entered the war with the recently acquired cruisers from Germany, the Yavuz Sultan Selim (formerly SMS Goeben) and the Midilli (formerly SMS Breslau) launching a naval raid on the Russian port of Odessa, thus engaging in a military action in accordance with its alliance obligations with Germany. Russia and the Triple Entente declared war on the Ottoman Empire.[15]

Bulgarian soldiers firing at incoming aircraft

Bulgaria was still resentful after its defeat in July 1913 at the hands of Serbia, Greece and Romania. It signed a treaty of defensive alliance with the Ottoman Empire on 19 August 1914. It was the last country to join the Central Powers, which Bulgaria did in October 1915 by declaring war on Serbia. It invaded Serbia in conjunction with German and Austro-Hungarian forces. Bulgaria held claims on the region of Vardar Macedonia then held by Serbia following the Balkan Wars of 1912–1913 and (from the Bulgarian point of view), the costly Treaty of Bucharest (1913).[16] As a condition of entering WW1 on the side of the Central Powers, Bulgaria was granted the right to reclaim that territory.[17][18]

In opposition to offensive operations by Union of South Africa, which had joined the war, Boer army officers of what is now known as the Maritz Rebellion "refounded" the South African Republic in September 1914. Germany assisted the rebels, some rebels operating in and out of the German colony of German South-West Africa. The rebels were all defeated or captured by South African government forces by 4 February 1915.

The Dervish movement was a rebel Somali movement which had existed since before World War I. It was led by Mohammed Abdullah Hassan, who was seeking the independence of Somali territories. The Dervish movement was supported by the Ottoman Empire and Germany, and also briefly by the Ethiopian Empire from 1915 to 1916.[19] Dervish forces fought against Italian and British forces in Italian Somaliland and British Somaliland during the Somaliland Campaign.

The Senussi Order was a Muslim political-religious tariqa (Sufi order) and clan in Libya, previously under Ottoman control, which had been lost to Italy in 1912. In 1915, they were courted by the Ottoman Empire and Germany and Grand Senussi Ahmed Sharif as-Senussi declared jihad and attacked the Italians in Libya and British controlled Egypt in the Senussi Campaign.

In 1915 the Sultanate of Darfur renounced allegiance to the Sudan government and aligned with the Ottomans. The Anglo-Egyptian Darfur Expedition pre-emptively in March 1916 to prevent an attack on Sudan and took control of the Sultanate by November 1916.

On 11 June 1916, while pursuing the Austro-Hungarian Army in Bukovina during the Brusilov Offensive, Russian forces inadvertently crossed into Romanian territory, where they overwhelmed the border guard at Mamornița and had a cavalry patrol disarmed and interned at Herța. Having no intention to force the hand of the Romanian Government, the Russians quickly left Romanian territory. The Romanian reaction to the Russian incursion left the Austro-Hungarian Minister to Romania, Count Ottokar Czernin, "fully satisfied".[20][21]

Belarus (Belarusian People's Republic)

The Belarusian People's Republic was a client state of Germany created in 1918.

Courland and Semigallia

The Duchy of Courland and Semigallia was a client state of Germany created in 1918.

Crimea (Crimean Regional Government)

The Crimean Regional Government was a client state of Germany created in 1918.

Don (Don Republic)

The Don Republic proclaimed by Don Cossacks on May 18, 1918 fought against the Bolsheviks; it was closely associated with the German Empire

Finland (Kingdom of Finland)

Finland had existed as an autonomous Grand Duchy of Russia since 1809 and the collapse of the Russian Empire in 1917 gave it its independence. Following the end of the Finnish Civil War, in which Germany supported the "White" against the Soviet-backed labour movement, in May 1918 there were moves to create a Kingdom of Finland. A German prince was elected but the Armistice intervened.

Kuban (Kuban People's Republic)

The Kuban People's Republic was a client state of Germany created in 1918.

Lithuania (Kingdom of Lithuania)

The Kingdom of Lithuania was a client state of Germany created in 1918.

Northern Caucasus (Mountainous Republic of the Northern Caucasus)

The Mountainous Republic of the Northern Caucasus was associated with the Central Powers.

Georgia (Democratic Republic of Georgia)

The Democratic Republic of Georgia declared independence in 1918 which then led to border conflicts between newly formed republic and Ottoman Empire. Soon after Ottoman Empire invaded the republic and quickly reached Borjomi. This forced Georgia to ask for help from Germany which they were granted. Germany forced the Ottomans to withdraw from Georgian territories and recognize Georgian sovereignty. Germany, Georgia and the Ottomans signed a peace treaty, the Treaty of Batum which ended the conflict with the last two. In return Georgia become a German "ally". This time period of Georgian-German friendship was known as German Caucasus expedition.

Poland (Kingdom of Poland)

The Kingdom of Poland was a client state of Germany created in 1916.[22] This government was recognized by the emperors of Germany and Austria-Hungary in November 1916, and it adopted a constitution in 1917.[23] The decision to create a Polish State was taken by Germany in order to attempt to legitimize its military occupation amongst the Polish inhabitants, following upon German propaganda sent to Polish inhabitants in 1915 that German soldiers were arriving as liberators to free Poland from subjugation by Russia.[24] The state was utilized by the German government alongside punitive threats to induce Polish landowners living in the German-occupied Baltic territories to move to the state and sell their Baltic property to Germans in exchange for moving to Poland, and efforts were made to induce similar emigration of Poles from Prussia to the state.[25]

Ukraine (Ukrainian State)

The Ukrainian State was a client state of Germany led by Hetman Pavlo Skoropadskyi, who overthrew the government of the Ukrainian People's Republic.[26]

United Baltic Duchy

The United Baltic Duchy was a German protectorate proposed by Germans in the former Courland, Livonian, and Estonian governorates. It briefly existed in 1918.

Azerbaijan (Azerbaijan Democratic Republic)

In 1918, the Azerbaijan Democratic Republic, facing Bolshevik revolution and opposition from the Muslim Musavat Party, was then occupied by the Ottoman Empire, which expelled the Bolsheviks while supporting the Musavat Party.[27] The Ottoman Empire maintained a presence in Azerbaijan until the end of the war in November 1918.[27]

Jabal Shammar

Jabal Shammar was an Arab state in the Middle East that was closely associated with the Ottoman Empire.[28]

Lij Iyasu, ruler of Ethiopia until 1916 pictured in his Ottoman-style turban

The Ethiopian Empire was officially neutral throughout World War I but widely suspected of sympathy for the Central Powers between 1915 and 1916. At the time, Ethiopia was one of the few independent states in Africa and a major power in the Horn of Africa. Its ruler, Lij Iyasu, was widely suspected of harbouring pro-Islamic sentiments and being sympathetic to the Ottoman Empire. The German Empire also attempted to reach out to Iyasu, dispatching several unsuccessful expeditions to the region to attempt to encourage it to collaborate in an Arab Revolt-style uprising in East Africa. One of the unsuccessful expeditions was led by Leo Frobenius, a celebrated ethnographer and personal friend of Kaiser Wilhelm II. Under Iyasu's directions, Ethiopia probably supplied weapons to the Muslim Dervish rebels during the Somaliland Campaign of 1915 to 1916, indirectly helping the Central Powers' cause.[29]

Fearing the rising influence of Iyasu and the Ottoman Empire, the Christian nobles of Ethiopia conspired against Iyasu over 1915. Iyasu was first excommunicated by the Ethiopian Orthodox Patriarch and eventually deposed in a coup d'état on 27 September 1916. A less pro-Ottoman regent, Ras Tafari Makonnen, was installed on the throne.[29]