I always thought that March 1st WAS the planned start date for Operation Barbarossa, as planned by a certain A. Hitler?
A reviewer of this book on amazon stated "tanks can't move through the mud of spring". Thought that was one of the reasons they were given tracks?
Metrocab
Hitler wanted to start the attack in spring but weather conditions/Balkan attacks [take your pick] delayed it.
Tanks are tracked to enable them to go through rugged or difficult terrain. However there are limits to every ability. The Russian spring mud, when all the snow that has fallen over the long winter and poor drainage in very flat terrain mean serious mud. Even the Soviets didn't move much during this period.
Furthermore, even if tanks could move through the mud their very little use without the infantry, artillery, supply and other support units which all move in trucks [if their lucky], with the aid of horses or under their own boot power.
If the Germans had attacked in March their advances would have been seriously slowed and if their panzers had been able to move and pushed ahead you might have seen at least 1-2 spearheads isolated and totally destroyed.
Steve