European theatre of World War I Although considerable conflict took place outside Europe , the European theatre was the main theatre of operations during World War I and was where the war began and ended . During the four years of conflict , battle was joined by armies of unprecedented size equipped with new mechanized technologies , leaving millions dead or wounded . Overview . The European theatre is divided into four main theatres of operations : the Western Front , the Eastern Front , the Italian Front , and the Balkans Front . Not all of Europe involved in the war . Nor did fighting take place throughout all of the major combatants territory . The United Kingdom was nearly untouched by the war . Most of France was unaffected , as was most of Germany and Italy . Some large countries in Europe remained neutral for the entire war such as Sweden and Spain – the Great War passed them by without much impact . On the other hand , some countries were conquered ( Serbia , Belgium , Romania ) . Other countries like Russia and the Ottoman Empire saw armies marching over much of their lands , with a great deal of resulting devastation . Although the United States did join the war , due to Great Britain ' s control over the Atlantic Ocean , the only fighting for the U . S . Army was in Europe on the Western Front . The American army was transported by ship across the ocean so it could fight the Germans in France . Western Front . The Western Front was the scene of continuous combat from the start of the war until the last day of the war , November 11 , 1918 . The fighting on the Western Front was mainly confined to the north - eastern part of France as well as Belgium . Most of France was not fought over , and the Netherlands remained neutral for the entire war . The Western Front involved the allied powers of France , the British Empire , Belgium , and America fighting against the armed forces of the German Empire . Eastern Front . The fighting on the Eastern Front was primarily contested by the German army and the Austro - Hungarian army on one side and the forces of the Russian Empire and Romania on the other . The Eastern front covered a very large territory , from the Baltic in the north to the Black Sea in the south and from Prussia and Galicia in the west to Latvia and Minsk to the east . The fighting on this front ended early , with the last significant military operation taking place in the autumn of 1917 . The two Russian Revolutions of 1917 forced Russia out of the war . The Bolshevik government that took power in November 1917 had promised an end to the war and that government signed the Treaty of Brest - Litovsk which ended the war for Russia in March 1918 . Italian Front . The Italian Front covered only a small part of northern Italy and the western border of Austria - Hungary . The fighting here began in 23 May 1915 and lasted till 3 November 1918 . Most of the fighting was concentrated on a very small bit of land between the Alps and the Adriatic , near the town of Trieste . The fighting primarily involved Italy and Austria - Hungary but also included smaller contingents from France , the UK , and the US ( who fought on the side of Italy ) , and Germany ( who was allied with Austria - Hungary ) . Balkans Front . The Balkans Front covered all of Serbia , Montenegro , Albania , and Romania . It also covered northern Greece , the western part of Bulgaria , and the south and eastern parts of Austria - Hungary . Very little fighting took place in this theatre for long periods of time . It was considered a lesser theatre of war by the Great Powers . The Central Powers of Austria - Hungary , Germany , Bulgaria , and the Ottoman Empire were opposed by the allied powers of Serbia , France , the United Kingdom , Romania , Russia , Montenegro , and Greece . Naval conflict . Because of the dominance of the British and French navies , only limited fighting took place in the seas around Europe . The German U - Boat fleet tried to sink British merchant ships , with some success early in the war . German U - Boats had only moderate cruising range in this war and operated mostly in the North Sea , the Irish Sea and in the Mediterranean . The German U - Boat threat was drastically reduced when the British finally adopted a convoy system in early 1917 . There was one great battle in the waters near Europe : the Battle of Jutland 31 May 1916 – 1 June 1916 between the German High Seas Fleet and the British Grand Fleet . This was one of the largest sea battles in world history though , in some respects , the battle was inconclusive . In the Adriatic , some very limited sea combat took place between the navy of Austria - Hungary and the Allied navies of France , Britain , and Italy . The strategy of the Allies was to blockade the Adriatic and monitor the movements of the Austrian fleet . In general , this strategy was successful but the Germans and the Austrians were able to send submarines out into the Mediterranean where they did some damage . The main sea base for the Austrian and German fleet in the Adriatic was Pola ( modern day Pula in Croatia ) . Japan , an ally of the United Kingdom , sent some destroyers to the Mediterranean and they were very effective in patrol and anti - submarine activity . By contrast the Italian Navy was " languid and apathetic " ( Cyril Falls " The Great War " p . 295 ) . The only significant naval battle occurred on 15 May 1917 when three Austrian cruisers under Captain Miklós Horthy staged a raid on some Italian and British transports near Valona Albania . The raid was a partial success but the raiders were nearly destroyed by shell fire from Italian ships that chased them back to Pola . In the Black Sea , the Russian fleet was dominant and it was led by two skilled commanders , Admiral Eberhart and then Admiral Kolchak ( who took over in 1916 ) . By the end of 1915 , the Russian fleet had nearly complete control of the sea . The Black Sea fleet was used mainly to support General Yudenich in his Caucasus Campaign . In the Baltic Sea , the Russian fleet was essentially inactive , hiding behind the belts of mines which stretched across the entry into the Gulf of Finland . So the German Baltic fleet dominated the sea and was of occasional use to the German army on the Eastern front .