Courland Pocket in the context of "Baltic Offensive"

The Baltic states—Estonia, Latvia and Lithuania—were occupied and annexed by the Soviet Union in 1940 and remained under its control until its dissolution in 1991. For a period of several years during World War II, Nazi Germany occupied the Baltic states after it invaded the Soviet Union in 1941.

The initial Soviet invasion and occupation of the Baltic states began in June 1940 under the Molotov–Ribbentrop Pact, made between the Soviet Union and Nazi Germany in August 1939, before the outbreak of World War II. The three independent Baltic countries were annexed as constituent Republics of the Soviet Union in August 1940. Most Western countries did not recognise this annexation, and considered it illegal. In July 1941, the occupation of the Baltic states by Nazi Germany took place, just weeks after its invasion of the Soviet Union. The Third Reich incorporated them into its Reichskommissariat Ostland. In 1944, the Soviet Union recaptured most of the Baltic states as a result of the Red Army's Baltic Offensive, trapping the remaining German forces in the Courland Pocket until their formal surrender in May 1945.

The end of World War II in Europe occurred in May 1945. Following the suicide of Adolf Hitler on 30 April, leadership of Nazi Germany passed to Grand Admiral Karl Dönitz and the Flensburg Government. Soviet troops captured Berlin on 2 May, and a number of German military forces surrendered over the next few days. On 8 May, Field Marshal Wilhelm Keitel signed the German Instrument of Surrender, an unconditional surrender to the Allies, in Karlshorst, Berlin. This is celebrated as Victory in Europe Day, while in Russia, 9 May is celebrated as Victory Day.

Some fighting continued after the German surrender. Some battles continued on the Eastern Front such as the Courland Pocket in western Latvia surrendering on 10 May, and the Prague offensive in Czechoslovakia ending on 11 May. On 25 May 1945, the Battle of Odžak ended in a Yugoslav Partisan victory. Following the conclusion in the European theatre, with the war continuing in the Pacific theatre.

The 51st Army (Russian: 51-я армия) was a field army of the Red Army that saw action against the Germans in World War II on both the southern and northern sectors of the front. The army participated in the Battle of the Kerch Peninsula between December 1941 and January 1942; it was destroyed in May 1942 with other Soviet forces when the Wehrmacht launched an operation to dislodge them from the peninsula. The army fought in the Battle of Stalingrad during the winter of 1942–43, helping to defeat German relief attempts. From late 1944 to the end of the war, the army fought in the final cutting-off of German forces in the Courland area next to the Baltic. Deactivated in 1945, the army was activated again in 1977 to secure Sakhalin and the Kuril Islands. Following the dissolution of the Soviet Union, the army continued in existence as a component of the Russian Ground Forces. The army was active during two periods from 1941 until 1997.

The Soviet Union (USSR) occupied most of the territory of the Baltic states in its 1944 Baltic Offensive during World War II. The Red Army regained control over the three Baltic capitals and encircled retreating Wehrmacht and Latvian forces in the Courland Pocket, where they held out until the final German surrender at the end of the war.

Operation Bagration (Russian: Операция Багратион, romanized: Operatsiya Bagration) was the codename for the 1944 Soviet Byelorussian strategic offensive operation (Russian: Белорусская наступательная операция «Багратион», romanized: Belorusskaya nastupatelnaya operatsiya "Bagration"), a military campaign fought between 22 June and 19 August 1944 in Soviet Byelorussia in the Eastern Front of World War II, just over two weeks after the start of Operation Overlord in the west. It was during this operation that Nazi Germany was forced to fight simultaneously on two major fronts for the first time since the war began. The Soviet Union destroyed 28 of the divisions of Army Group Centre and completely shattered the German front line. The overall engagement is the largest defeat in German military history, with around 450,000 German casualties, while setting the stage for the subsequent isolation of 300,000 German soldiers in the Courland Pocket.

On 22 June 1944, the Red Army attacked Army Group Centre in Byelorussia, with the objective of encircling and destroying its main component armies. By 28 June, the German 4th Army had been destroyed, along with most of the Third Panzer and Ninth Armies. The Red Army exploited the collapse of the German front line to encircle German formations in the vicinity of Minsk in the Minsk Offensive and destroy them, with Minsk liberated on 4 July. With the end of effective German resistance in Byelorussia, the Soviet offensive continued on to Lithuania, Poland and Romania over the course of July and August.