Estonia
World War II

A week before the outbreak of World War II, on 23 August 1939, Nazi Germany and the Stalinist Soviet Union signed the Molotov–Ribbentrop Pact. In the pact's secret protocol Poland, Romania, Lithuania, Latvia, Estonia and Finland were divided between USSR and Germany into "spheres of influence", with Estonia assigned to the Soviet "sphere". On 24 September 1939, the Soviet dictator Stalin presented the Estonian government an ultimatum demanding that Estonia immediately sign a treaty that would allow the USSR to establish military bases in Estonia, or else face war. The Estonian government decided to avoid military conflict, and a " mutual assistance treaty " was signed in Moscow on 28 September 1939. On 14 June 1940 the Soviet Union instituted a full naval and air blockade on Estonia. On the same day, the airliner Kaleva was shot down by the Soviet Air Force. On 16 June, the USSR presented an ultimatum demanding completely free passage of the Red Army into Estonia and the establishment of a pro-Soviet government. Feeling that resistance was hopeless, the Estonian government complied and, on the next day, the whole country was occupied. On 6 August 1940, Estonia was annexed by the Soviet Union as the Estonian SSR.

The USSR established a repressive wartime regime in occupied Estonia. Many of the country's high-ranking civil and military officials, intelligentsia and industrialists were arrested. Soviet repressions culminated on 14 June 1941 with mass deportation of around 11,000 people to Russia. When Operation Barbarossa (accompanied by Estonian guerrilla soldiers called " Forest Brothers ") began against the Soviet Union on 22 June 1941 in the form of the " Summer War " (Estonian: Suvesõda), around 34,000 young Estonian men were forcibly drafted into the Red Army, fewer than 30% of whom survived the war. Soviet destruction battalions initiated a scorched earth policy. Political prisoners who could not be evacuated were executed by the NKVD. Many Estonians went into the forest, starting an anti-Soviet guerrilla campaign. In July, German Wehrmacht reached south Estonia. The USSR evacuated Tallinn in late August with massive losses, and capture of the Estonian islands was completed by German forces in October.

Initially, many Estonians were hopeful that Germany would help to restore Estonia's independence, but this soon proved to be in vain. Only a puppet collaborationist administration was established, and occupied Estonia was merged into Reichskommissariat Ostland, with its economy being fully subjugated to German military needs. About a thousand Estonian Jews who had not managed to leave were almost all quickly killed in 1941. Numerous forced labour camps were established where thousands of Estonians, foreign Jews, Romani, and Soviet prisoners of war perished. German occupation authorities started recruiting men into small volunteer units but, as these efforts provided meagre results and the military situation worsened, forced conscription was instituted in 1943, eventually leading to formation of the Estonian Waffen-SS division. Thousands of Estonians who did not want to fight in the German military secretly escaped to Finland, where many volunteered to fight together with Finns against Soviets.

The Red Army reached the Estonian borders again in early 1944, but its advance into Estonia was stopped in heavy fighting near Narva for six months by German forces, including numerous Estonian units. In March, the Soviet Air Force carried out heavy bombing raids against Tallinn and other Estonian towns. In July, the Soviets started a major offensive from the south, forcing the Germans to abandon mainland Estonia in September and the Estonian islands in November. As German forces were retreating from Tallinn, the last pre-war prime minister Jüri Uluots appointed a government headed by Otto Tief in an unsuccessful attempt to restore Estonia's independence. Tens of thousands of people, including most of the Estonian Swedes, fled westwards to avoid the new Soviet occupation.

Overall, Estonia lost about 25% of its population through deaths, deportations and evacuations in World War II. Estonia also suffered some irrevocable territorial losses, as the Soviet Union transferred border areas comprising about 5% of Estonian pre-war territory from the Estonian SSR to the Russian SFSR.
length_constraints:number_sentences[4], punctuation:no_comma