The Eastern Front refers to a theatre of war during the first World War in Central and, primarily, Eastern Europe. The term is in contrast to the Western Front. Both terms refers to Continental Europe. Despite the geographical separation, the events in the two theaters strongly influenced each other.
The geography of Eastern Europe in general has played a key role in how both World Wars' Eastern Front conflicts played out. Eastern Europe is, for the most part, physically similar to Western Europe as both belong to the same European plain. The key difference was the level of economic development. While Belgium and Northern France were among the most industrially advanced areas in the world, with excellent road and rail networks, Eastern Europe was undeveloped in comparison. Furthermore the length of the front in the East was much longer in the West. The theatre of war was roughly delimited by the Baltic Sea in the West and Moscow in the East, a distance of 1,200 kilometers, and Saint Petersburg in the North and the Black Sea in the South, a distance of more than 1,600 kilometers. This had a drastic effect on the nature of warfare. While World War I on the Western Front developed into trench warfare, the battle lines on the Eastern Front were much more fluid and Trench War never truly developed. This was because the greater length of the front ensured that the density of soldiers in the line was lower so the line was easier to break. Once broken, the sparse communication networks made it difficult for the defender to rush reinforcements to the rupture in the line to mount a rapid counteroffensive and seal off a breakthrough. In short, on the Eastern front the side defending did not have the overwhelming advantages it had on the Western front. Because of this, front lines in the East kept on shifting throughout the conflict, and not just near the beginning and end of the fighting, as was the case in the West. In fact the greatest advance of the whole war was made in the East by the German army in the summer of 1915.
At the outbreak of the war, Tsar Nicholas II appointed his cousin, Grand Duke Nicholas as commander in chief. Although not without ability, the Grand Duke had no part in formulating the war plans. This led to disaster.
The war in the East began with the Russian Army attempting to invade Germany's East Prussia province and the Austro-Hungarian province of Galicia. The first effort quickly turned to a disaster following the Battle of Tannenberg in August 1914. The second was completely successful, with the Russians controlling almost all of Galicia by the fall of 1914. This early Russian success in 1914 on the Austro-Russian border was a reason for concern to the Central Powers and caused considerable German forces to be transferred to the East to take pressure off the Austrians. At the same time the effectiveness of the Russian army rapidly declined as the underdeveloped Russian arms industry proved unable to meet the demands of the front.
To eliminate the Russian threat the Central Powers began a successful offensive in Galicia in the spring of 1915. This soon turned into a general advance and then a strategic retreat by the Russian army. By 1915 the Russians had been expelled from Russian Poland and hence pushed hundreds of kilometers away from the borders of the Central Powers, removing any threat of Russian invasion of Germany or Austria-Hungary. At the end of 1915 the main part of the front reached a line which in general outline did not change until the Russian collapse in 1917.
In 1916 the Russians attempted a large counteroffensive under the leadership of general Brusilov (Brusilov Offensive). The attack, aimed against the part of the front held by Austro-Hungarians, was initially a spectacular success. However, a successful counteroffensive by German units halted the Russian attack. Also during 1916, Romania entered the war on the side of the Entente, but was quickly overrun by the German armies.
By 1917, the Russian economy finally neared collapse under the strain of the war effort. While the equipment of the Russian armies actually improved due to the expansion of the war industry, the food shortages in the major urban centres brought about a revolution. The large war casualties, nearly 2 million dead by 1917, also created disaffection and mutinous attitudes in the army. Two revolutions that year would cause first Tsar Nicholas to abdicate, and a few months later for the Communist Bolsheviks to seize power under their leader Vladimir Lenin. Lenin would quickly push for withdrawal from the War.
In March, 1918, the Treaty of Brest-Litovsk was signed and the Eastern Front collapsed. The Germans were finally able to transfer many of their divisions in the East to the West, in order to use thus gained numerical superiority to mount an offensive in France in 1918. However, by then the arrival of American units in Europe was sufficient to offset the German advantage. Even after the Russian collapse about a million German soldiers remained tied up in the East until the end of the war, attempting to run a short-lived addition to the German empire in Europe. In the end, Germany and Austria would end up losing their captured lands under the Treaty of Versailles.
The Russian casualties in the First World War are difficult to estimate, due to poor quality of available statistics. Some official Russian sources list 775,400 battlefield fatalities. More recent Russian estimates give 900,000 battlefield deaths and 400,000 dead from combat wounds, for a total of 1.3 million dead. This is about equal to casualties suffered by France and Austria-Hungary and about one-third less than those suffered by Germany. When Russia withdrew from the war, 3.9 million Russian POWs were in German and Austrian hands. This by far exceeded the total number of prisoners of war (1.3 million) lost by the armies of Britain, France and Germany combined. Only the Austro-Hungarian army, with 2.2 million POWs, came close. In other words, for every 100 Russians that fell in battle, 300 surrendered. For the British army, the comparable figure was 20, for French 24, and for German 26. In other words, Russians surrendered at the rate twelve to fifteen times that of Western soldiers.