I was recently re-watching the World at War documentary series and Specifically the episode about Barbarossa. In this episode they mention the Allied encouraged Yugoslav coup d'etat, which kicked the Nazi favored government out of power in the country.
In the series they mentioned that the following invasion of Yugoslavia by the Axis delayed the commencement of Operation Barbarossa by 5 weeks.
Does anyone know how significant this was? If the Germans had an extra 5 weeks at the start of their Campaign could they have struck a killing blow before the Russian winter and Siberian divisions pushed them back, or were the Germans at the limits of their supply anyway?
I appreciate that these kind of 'What If' questions are often impossible to answer but I would be very interested if anyone knew of any academic or amateur works (or had an Opinion) on this matter.
Depends on what you mean by successful. A five week delay certainly let the USSR be better prepared, but it likely would have played out the same way.
The big difference five weeks might have made was avoiding the rasputitsa in October 1941. Rasputitsa refers to the muddy seasons that occur in Russia during its rainy autumn and snow melting spring. Germany relied on its mobile warfare to push quickly through enemy lines and encircle enemy forces. In fact, in late September 1941, Hitler diverts forces headed towards Moscow to assist with Kiev. Kiev was a major German victory with some 700,000 Soviet casualties versus 128,000 German casualties. However, that delay put those forces back on track for Moscow in October, just as the muddy season began. The mud basically stopped the Germans in their tracks. Tanks and trucks were literally stuck in the mud. Their advance slowed to a crawl and it bought Moscow valuable time to reinforce the city. It wasn't until mid-November that the ground froze and the offensive could continue. However, that winter just so happened turned out to be the coldest recorded winter in the 20th century - Russian winter was always a problem and this was the coldest one ever. By January 1942, the Germans fell back in the first major defeat by the Soviets. Hitler dismissed many of his military advisors for their failure to take Moscow and began to take firmer personal control of the military command and surrounded himself with less experienced yes-men. Of course Stalin got overly confident about the victory and it lead him to launch a series of failed offensives in the spring, but that's a different story.
So had the invasion occurred 5 weeks earlier, it's possible that Germany might have been able to take Moscow before the muddy season began. While that would have been a demoralizing blow to the Soviets, it likely wouldn't have resulted in a surrender. The mud season and then then coldest winter ever were still coming and the issues caused by that would stop the Germans, regardless of Moscow. The only other thing we can speculate is that it might have lead to a more cautious Stalin and that Hitler might have kept some of his better advisors around.
I'd direct to this answer by u/shnu for a good discussion about whether a Soviet surrender was ever realistic. I think big picture that does a decent job of answering your question. It might've made a difference in the short term, but long term it's unlikely anything would have changed.