Before World War II,  the treaty of Versailles was signed, making Germany pay war fees and could no longer have an army. However, Adolf Hitler broke these rules and began to invade Poland. So, on September 17th, 1939, Russia joined World war II despite losing many soldiers in the great war and the Russian Civil War due to Germany invading Russia.

Let's jump back in time before WWI. Frenz Ferdinand, the heir to Austria-Hungary and his wife, was assassinated by Gervillo Philips in Serbia. The assassination caused A war between Austria-Hungary and Serbia, with each side calling in allies until it caused World War I. It kept going until June 28th, 1919; both sides, the Allies and Central powers, signed a treaty named the treaty of Versailles, stating Germany must pay War fees and could no longer have an army. At the same time, the other countries expanded their land and set boundaries that will later cause WWII when Adolf Hitler comes to power.

Left top-Archduke Franz Ferdinand, Bottom left- The Austria- Hungary flag, Middle top- Newspaper about the treaty, Bottom middle-Archduke Ferdinand's wife, Top right- WWI german flag, Bottom right- Adolf Hitler