The term logistics refers to the management of the flow of goods between the point of origin and the point of use. Military logistics would be the supply line to re-enforce the troops where ever they might be. Logistics include services such as medical, mechanical and construction. The word itself comes from the Greek word logos, which roughly means logic. No one is quite sure how this became a military term but having a method to supply an army is definitely logical.
To accomplish anything in life one must be both willing and able. This applies in war too. There can't be war unless both sides are both willing and able to fight. Logistics play a major role in providing the soldiers their ability to fight. When Napoleon Bonaparte said, "An army marches on its stomach," he was referring to the importance of logistics.
When neighboring countries go to war with each other, logistics can be supplied overland. But most of the time logistics are best supplied by sea, as it's faster, cheaper and more efficient (carries more) than land routes. An old Greek saying regarding logistics says, "He who rules the seas rules the world." Obviously, this is why having a strong navy is so important.
It's difficult to destroy an enemy's will, as his commitment is very personal... inside his mind, heart and soul. Therefore, it's much easier to destroy his ability to fight by cutting off his supply line. Once he realizes he has lost his ability to continue, he knows he has no chance of winning. Unless he believes his death will be for the greater good, he will surrender. In almost every war ever fought in human history, ultimately logistics decided the outcome. Siege warfare is a logistical war. One side surrounds their enemy and, providing no one comes to their rescue, starves them into surrendering.
Understanding the battles of WWII, like any war, is to study the logistics on both sides. Many of the battles were about one side attacking the other side's logistics.
The British Empire and the United States not only had more resources than the Axis powers, but had superior logistics as well. To a lesser extent, so did the Soviet Union. The truth is the Axis powers were doomed from the start.
Hitler knew this, but he gambled that his blitzkrieg tactics would give him quick victories, rendering long term logistics unnecessary. He proved to be right when he took Poland, France, the low countries and Norway. But after that, he found out just how wrong he was, as his war became a prolonged war.
The Battle of the Atlantic was about Hitler trying to cut the logistics pouring into England. Seeing how he didn't have a strong enough navy to establish a blockade around the British Isles, he relied on his U-boats to do the job. They sunk a lot of Allied ships, but never enough to seriously cripple the flow of British supplies.
Most of the Allied Air Force missions were attacks on Axis logistics. They hit their factories, railroads and marshalling yards (military term for distribution centers). Bombing their refineries proved to do more to win this war than any other one thing. The Germans literally ran out of gas.
Mussolini also understood logistics, but he and his generals weren't very good at it. So many times the Italians would launch an offensive and everything would go as planned and then suddenly, due to their own failures, they would run of something and lose the battle. Many historians say the Italians were poor soldiers because their hearts weren't into it. They should have said that due to poor logistics, the Italian soldiers lost their ability to fight and, therefore, they lost their will to fight.
The war in the Pacific to a certain extent was a logistical war. The Allies quickly established solid shipping lanes for their logistics while sinking as many Japanese cargo ships as they could. In Japanese culture, attacking unarmed merchant vessels was regarded as highly dishonorable. They felt all wars should be fought honorably by soldiers on the battlefield. As the war progressed, they realized that if they were to have any chance of winning, they had to start attacking Allied logistics, too.
Even General Douglas MacArthur's famous "island hopping" campaigns were a form of siege warfare. His forces would cut off the logistics to large Japanese troop concentrations, thus starving them into submission.
An old military adage says that "amateurs study tactics, professionals study logistics." I don't know who first said that, but just about every soldier has repeated it, including Omar Bradley and Colin Powell. The first time I heard that was from my own father, Lt Col Charles Arnett (a three war veteran), who added, "Without logistics our combat soldiers don't have a chance."