08 Imperial Rivalries and the First World War

Imperial competition and nationalism

In the late nineteenth and early twentieth centuries, European powers competed for colonies, trade, strategic routes, and international influence. Britain and France controlled vast overseas empires. Germany, unified in 1871, sought greater global status and expanded its own empire. Colonial disputes, including crises over Morocco, heightened suspicion, and Germany's naval expansion challenged Britain's maritime dominance.

Imperial rivalry contributed to international tension, but did not make war inevitable. Some disputes were settled by negotiation, and several imperial disagreements had eased by 1914. Competition nevertheless reshaped diplomatic relationships and sharpened fears among the great powers.

Nationalism was especially destabilizing in the Balkans, where the decline of Ottoman power encouraged the formation of new states and competing territorial ambitions. Serbia sought to unite South Slavs, while Austria-Hungary feared that Serbian influence could weaken its multiethnic empire. Russia supported Serbia partly because it claimed a broader role as protector of Slavic peoples, bringing regional rivalries into direct contact with major-power interests.

Alliances and military readiness

Alliances, concerns about military readiness, and arms races made an international crisis more dangerous. Germany and Austria-Hungary were linked with Italy in the Triple Alliance, although Italy did not join them when war began. France and Russia were allies, and Britain had reached understandings with both. These relationships were often called the Triple Entente, though the agreements were not all identical formal military alliances.

Governments worried about encirclement and shifting power. Arms races and plans for rapid mobilization meant that once leaders began moving their forces, a crisis could escalate quickly. The alliance system helped spread the conflict, but did not make escalation automatic.

From assassination to European war

On June 28, 1914, Gavrilo Princip, a Bosnian Serb nationalist, assassinated Archduke Franz Ferdinand, heir to Austria-Hungary's throne, in Sarajevo. Austria-Hungary blamed Serbia and, with German backing, delivered a severe ultimatum. Serbia accepted most demands but rejected some that threatened its sovereignty.

Austria-Hungary declared war on Serbia on July 28. Russia mobilized in support of Serbia; Germany declared war on Russia on August 1 and on France on August 3. German forces invaded neutral Belgium on August 4 as they advanced toward France, and Britain entered the war that day. Decisions by governments during the July Crisis transformed a regional conflict into a European war.

Trench warfare and global attrition

Germany's advance through Belgium was checked at the First Battle of the Marne in September 1914. Neither side then found a quick route to victory on the Western Front. Armies built continuous trench lines across northern France and Belgium. Machine guns, artillery, barbed wire, and defensive positions made attacks costly, producing a long war of attrition in which each side tried to exhaust the other's soldiers, supplies, and capacity to keep fighting.

Industrial production and mass mobilization sustained the armies. Aircraft, poison gas, submarines, and later tanks expanded the forms of warfare. The conflict was global as well as European: British and French empires drew on troops and resources from colonies and dominions, and fighting took place in Africa, the Middle East, and at sea as well as on the main European fronts. Japan joined the Allies in 1914, the Ottoman Empire entered on the side of the Central Powers later that year, and Italy joined the Allies in 1915.

In 1916, Verdun and the Somme became emblematic battles of attrition. Verdun lasted more than nine months. The Somme offensive was launched in part to relieve pressure on the French at Verdun. It caused enormous casualties but did not achieve the decisive breakthrough its planners sought. On the Somme's first day, July 1, 1916, the British Army suffered about 57,000 casualties.

The balance shifts and the fighting ends

The balance changed in 1917. Germany resumed unrestricted submarine warfare, attacking shipping in an effort to weaken Britain; this helped bring the United States into the war in April. Russia's revolutions led it to withdraw from the conflict, and the new Bolshevik government signed an armistice with Germany in December.

In 1918, Germany launched major offensives in the west. Fresh American forces and Allied counterattacks then shifted momentum, and the Allies' Hundred Days Offensive drove German forces back. An armistice ended the fighting on November 11, 1918.

Imperial competition, shifting alliances, arms races, and nationalism created an unstable international environment, particularly in the Balkans. The assassination at Sarajevo set off the crisis, but government decisions transformed it into a general war. Trench warfare and industrial resources made the conflict prolonged and destructive, while imperial participation and fighting across several regions made it global. Russia's withdrawal, U.S. entry, and the Allied advance on the Western Front shaped the war's final phase.