Crushing their enemies with Blitzkrieg tactics, hard pressing armored units and mechanized formations, the German Wehrmacht was at its best on the offensive. Battle of annihilation would be their favorite doctrine. That being said, it could prove to be very dangerous to underestimate the defensive capabilities of the German army. Compared to the Allies, Germany did not have a lot of ships but in the depths of the oceans roamed fearsome packs of wolves... ready to strike at the their prey.
Although joining the World War 2 later than the other major powers, the USA had been preparing their production lines and supporting their allies for years. Completely outproducing their Axis enemies, the Americans were eventually able to launch offensive operations of epic proportions in all theaters. High up in the skies glided their Flying Fortresses... and they weren't delivering the mail.
Completely underestimated by the Allies, the Japanese Imperial Army and Navy swept across South-Asia and the Pacific in a lightning war of their own. Initially the Japanese had complete air superiority in the area and a fearsome navy which included the heaviest battleships ever constructed. When fighting a defensive war to protect the home island, the Japanese would dig in and fight a bitter fight to the very end. When that wasn't enough, driven by honor and loyalty, no sacrifice was considered too big.
At the outbreak of World War 2, although large on paper, the forces of the Soviet Union were badly equipped, trained and organized. This would change fast. Forged through fire and blood during the Great Patriotic War, the Red Army would soon become the mightiest war machine the world had ever seen. What's more, with their seemingly endless manpower and access to natural resources, the Soviets could produce more tanks, guns and aircraft... than any of their enemies.
The vast empire was caught off guard when the World War 2 broke out, but adapted quickly to new types of warfare. With their formidable fleet, advanced aircraft and incredible stubbornness, the British forces never gave an inch without a fight. The British also had an ace up their sleeve when it came to the gathering of intelligence. For the Allies this would prove to be... one of the mightiest weapons of all.
Before World War 2 many believed that the French had the most powerful military in Europe, but they were not prepared for the German Blitzkrieg advance. Although defeated, they did not give up the fight. The Free French Forces continued the fight against the Axis on foreign soil while The French Resistance disrupted and demoralized the German occupation forces at home. Both forces played a vital role in the liberation of France which started in June 1944 following the Allied invasion of Normandy.
While not ready for a long lasting conflict at the outbreak of the war, Italy tried to seize the opportunity believing that the British Empire was about to collapse from the German offensive. With ambitions to restore Italy to the status of the old Roman Empire, the Italian forces were concentrated on major offensives in the Africa and the Middle East. Supported by the threat of the formidable Italian fleet in the Mediterranean, initially this seemed to be working. But Britain didn't surrender and Italy was about to get bogged down in a long, bloody and bitter conflict.
Poland had prepared for the invasion from Germany for years but was unable to defend against superior forces from the West and the Soviets from the East. With their homeland occupied, the Polish forces continued their fight in exile. Before and during World War 2, Polish intelligence gathering and crypto-analysis experts contributed significantly to cracking the famous Enigma code. Their exiled forces fought fiercely during the Battle of Britain and other campaigns alongside their allies. Polish forces also continued the fight in their occupied homeland underground, most famously during the Warsaw uprising, the most significant military resistance in WW2-Europe. They never surrendered.