Most of Soldier X takes place on the Eastern Front, a theatre—or area—of World War II fought between the Soviet Union and Nazi Germany. Many countries engaged in this front, including most of Central, Eastern, Northeast, and Southeast Europe, particularly Poland. It is the primary theatre of war for World War II, hosting most of the combat and 30 million of the 70+ million deaths attributable to the war. The conflict between Germany and the USSR began with Operation Barbarossa, when Nazi Germany and their allies invaded the Soviet Union by bombing cities in Poland, breaking the preexisting pacts between the two nations. Nazi Germany believed that Russia was necessary for their principle of Lebensraum—or living space for German people—and intended to exterminate the native Russians, eradicate communism, and utilize Russian resources for their own purposes. It is unknown whether Joseph Stalin intended to invade Germany before Operation Barbarossa in turn, but the question remains hotly debated in the interest of analyzing the Soviet Union’s role in the greater war.

Germany’s losses during the battles in Operation Barbarossa likely led to their ultimate loss of the entire world war. While Germany was more resourced for the war, the Russian army’s familiarity with the territory and tenacity is attributed to their victory despite the latter’s heavy losses.