Several countries changed allegiance during World War II, most notably Italy, Romania, Bulgaria, and the Soviet Union, shifting from the Axis to the Allies as the tide of war turned, while Finland fought both sides at different times, and France was divided between the collaborating Vichy government and the Free French.
You already mentioned the Soviet Union (which changed sides relative to Germany (due to the German invasion) and later relative to Japan (invading Manchuria). In addition to them, Finland changed sides twice (relative to Germany) or once (relative to the Soviet Union), and France twice (relative to Germany).
Italy has a unique distinction in both World Wars: it switched sides! In 1914, when World War I began in Europe, Italy was a Central Power allied with Germany and Austria-Hungary. The following year, however, Italy entered the war as an Allied Power, fighting against Austria.
Popular support for Romania's participation in the war faltered, and the German–Romanian fronts collapsed under the Soviet onslaught. King Michael of Romania engineered the 1944 Romanian coup d'état that deposed the Antonescu regime and put Romania on the side of the Allies for the remainder of the war.
Mussolini was deposed following the invasion of Sicily in 1943, and Italy formally changed sides and joined the Allies later that year, though Rome would not be liberated until June 1944.
From the Finnish POV, they didn't switch sides: both wars were against the USSR, and the Continuation War was portrayed as a necessary or at least convenient continuation of the Winter War. From the perspective of Finland's relationship with the Soviet Union, Germany and Britain changed sides.
The Italians may have spent some time on the wrong side of World War 2, but the ultimate betrayal of Hitler contributed to a win for the Allied Forces and the eventual downfall of Germany!
(Only answering for ww2) I'll just post that only a few countries remained officially neutral throughout the entire war. They included Sweden, Switzerland, Spain, Portugal, Ireland, Yemen, Saudi Arabia and Afghanistan as well as the microstates of Andorra, Liechtenstein, and Vatican City.
Ever since Mussolini began to falter, Hitler had been making plans to invade Italy to keep the Allies from gaining a foothold that would situate them within easy reach of the German-occupied Balkans. On the day of Italy's surrender, Hitler launched Operation Axis, the occupation of Italy.
(Paul) Joseph Goebbels – One of Adolf Hitler's closest associates and most devout followers, known for zealous oratory and antisemitism.
During World War II, the Swiss were neutral and generally speaking maintained that position, meaning that they did not declare war or offer military assistance to either power, and while they traded, even in goods that had military purposes, they did not openly favor one side over the other (which would have given them ...
The 'D' in D-Day simply stands for "Day," used as a military placeholder for the start date of a major operation, with "D-Day" meaning "the day" an attack begins, and "D-2" meaning two days before. While many theories exist (like "Deliverance" or "Doom"), the term is a generic code, and the Normandy invasion on June 6, 1944, became the most famous event known as D-Day.
He believed that Adolf Hitler could not be trusted and that any agreement with the Nazis would only lead to further destruction down the line. Churchill argued that negotiating would mean accepting Nazi domination of Europe, which he saw as morally and strategically unacceptable.
On September 28, 1918, in an incident that would go down in the lore of World War I history—although the details of the event are still unclear—Private Henry Tandey, a British soldier serving near the French village of Marcoing, reportedly encounters a wounded German soldier and declines to shoot him, sparing the life ...
WW2 soldiers carried condoms primarily for disease prevention (STDs like syphilis and gonorrhea) and for practical combat uses, such as keeping sand and mud out of their rifle barrels, protecting small items, or even as makeshift waterproof bags, although the weapon-protection use is sometimes exaggerated in popular culture. The military distributed them widely (often in "prophylactic kits") to maintain troop strength, recognizing the significant manpower lost to venereal diseases in past conflicts.
Conclusion. Portugal, Spain, Sweden, and Switzerland held to the concept of armed neutrality, and continuously amassed soldiers to defend their nation's sovereignty from potential invasion.
It is a little known fact the Mexico Air Force fought alongside the United States Army Air Force in the South Pacific during World War II. Mexico accepted a U.S. invitation to provide Mexican Air Force units in the war against Japan shortly after the Japanese attack on Pearl Harbor.
Sweden's neutrality was confirmed and defined by an exchange of letters between King Gustav and Adolf Hitler that same month. Swedish wartime diplomacy sought to ward off German invasion by adopting a neutrality that sacrificed some of Sweden's independence and made significant concessions to Germany.
The Nazis considered Jews to be their number one enemy. During World War II, Nazi Germany and its allies and collaborators murdered six million Jews in a genocide now known as the Holocaust.
German troops began surrendering by the thousands. The rapidly shrinking eastern pocket surrendered on April 16, followed two days later by the remains of the western pocket. More than 300,000 Germans became prisoners of war, constituting the largest single German surrender in western Europe during World War II.
Located in Europe, Italy has been considered a major European power since its unification in 1860. Its main allies are the NATO countries and the EU states, two entities of which Italy is a founding member.
The Soviet Union suffered the most deaths in World War II, with estimates ranging from 22 to 27 million fatalities (military and civilian), followed by China, with around 20 million deaths, making these the two nations with the highest human cost from the war. Poland also experienced catastrophic losses relative to its population, and Germany and Japan also had immense casualties.
One of the main considerations that led the Swedish government to declare Sweden a non-belligerent state was concern that they might otherwise lose control of the internal situation in Sweden. The Soviet demands on Finland in the months prior to the outbreak of war had roused public opinion.
Leningrad, along with Moscow and Kiev, was one of the major objectives of the German offensive launched on 21 June 1941, but the city was not taken during the attack.