On June 22, 1941, Adolf Hitler launched a merciless attack against his so-called ally, the Soviet Union. In December 1941, after only five months, Operation Barbarossa, launched by the Nazis, failed. The Nazi Party ultimately met its demise, due to the failure of Operation Barbarossa, due to a combination of Hitler's arrogance towards the Soviets and the Soviet response, but above all the greater mistake of Hitler: dispersing his troops too widely across a colossal Russia. Hitler wrote in his book Mein Kampf that he would liquidate the Treaty of Versailles. The Treaty of Versailles, among other things, stipulated that Germany could only have six battleships, only 100,000 troops, and made no allowance for aircraft. In 1939, Germany had nearly a million men, ninety-five battleships and eight thousand two hundred and fifty aircraft. This aroused the distrust of many countries around the world, including the Soviet Union. Stalin and the Soviet Union unsuccessfully attempted to conclude a collective security agreement, against Germany, with Britain and France. Negotiations for a peace agreement between Russia and Germany began soon after and proved successful. Stalin made this agreement with the aim of reconstituting the Red Army after the purge, but did not inform the Germans; but Hitler had his own plans and broke the Nazi-Soviet non-aggression pact on June 22, 1941 by launching a full-scale attack on the Soviet Union, officially triggering Operation Barbarossa. During Operation Barbarossa, Hitler's arrogance caused him to underestimate the power of the Soviet Union. William Shirer writes: "It is becoming even clearer," wrote Halder in his diary of August 11, "that we underestimated the strength of the middle of the paper in order to occupy the important center of communications and arms manufacturing , Moscow” (Mawdsley 86). It was the most fatal mistake made by Hitler in his campaign and campaign for Russia, and it ended up becoming the first major loss for Germany since World War I, and a huge blow to confidence of the entire Nazi Party. Operation Barbarossa was the start of the war. end of the Nazi party in Germany. Many historians believe that without Hitler's underestimation of the Red Army, the Soviet response, and, most importantly, Hitler's mistakes that led to the Russian Winter, Germany might well have emerged victorious. not only from Operation Barbarossa, but also from the Second World War. The reasons for failure, clear but not concise, show that many different strategic decisions could have changed the outcome, as well as many other things in today's world..