To date, World War II remains the most costly and deadliest conflict in human history.

While the war only lasted six years, more than 70 million people lost their lives worldwide. It may be the "Second" of the world wars, but it actually ranks first in terms of the size of armies, aircraft, tanks, and even small arms that were employed.

Every continent except Antarctica saw involvement in the war and was fought on the land, at sea, and in the air.

The United States earned a reputation for being "the arsenal of democracy," and in today's dollars, the war cost $4.1 trillion – equal to the value of Apple or Amazon four times over. To pay for the war, income tax rates for those making above $200,000 were raised to an astounding marginal tax rate of 94 percent.

Despite the fact that the United States spent one and a half times on defense as Germany in 1943, and ten times what Japan spent, during the war other countries not only had larger armies, but actually produced vast amounts of material.

The Largest Army and the Most Women Soldiers

By the end of the war there were more veterans in the Soviet Union than there were people living in Mexico. The Soviet military, while typically all labeled "Russians," were actually a multiethnic force that included not only Russians but also Ukrainians, Byelorussians, Lithuanians, Poles, Georgians, Jews, Armenians as well as countless other ethnicities.

Of some 190 million people, more than 11 percent served in the military and the vast majority of those were in the Red Army. During the war, some 30 million men were conscripted and put in uniform in the Soviet Union, and that was in addition to the 4.8 million that were already serving when Germany invaded in 1941. Additionally, the Soviet Union was one of the only nations that saw women take on front line combat roles, and more Soviet women served in the Red Army than Frenchmen who served under Charles de Gaulle!

Greatest Casualties

In addition to fielding the largest military during the war, the Soviet's had the unfortunate distinction of suffering the most losses. Some 10.7 million soldiers were killed, and a total of 24 million Soviet citizens gave their lives during the war.

Soviet leader Joseph Stalin has been quoted as saying, "To the defeat of Nazism, the British gave Time, the Americans gave Money, and the Soviet Union gave Blood." It is debatable whether Stalin actually said those words, but regardless it certainly rings true.

M4 Sherman Tank

Where the United States and the arsenal of democracy delivered was in tanks. The M4 Sherman may not have been the best of the tanks used in World War II, but between 1942 and 1945 more than 50,000 were produced. It was the only tank to be used in all combat theaters, and not just with the United States.

The Sherman saw use with the British, Canadians and Free French; the tanks were also deployed for use by China and even the Soviet Union. The American tanks may have been outgunned and outclassed by Germany's late war counterparts, but the Sherman proved easier to maintain and could be fixed on the battlefield. The superior numbers certainly helped turn the tide and ensured the defeat of the Nazis.

The Most Warbirds

The B-17 may get all the glory, but during the bombing campaigns against Germany, as well as Japan, the true workhorse proved to be the aptly named B-24 Liberator. Some 12,000 B-24s saw service with the United States Army Air Forces during the war. Like the Sherman it was used in every theater of operations.

The arsenal of democracy may have produced those bombers, but it was Soviet factories that rolled out the most combat aircraft of the war: the Illyushin IL-2. With more than 36,000 built, that ground-attack aircraft remains the most produced warplane in history. That number is all the more impressive considering that less than 250 were built when Germany invaded in June 1941.

The Most Widely Used Small Arm

World War II saw rapid development of new small arms, including the adoption of the first semi-automatic battle rifle with the American M1 Garand, and the first "assault rifle" with the German StG-44. Yet, it was the 19th century designed Mosin-Nagent, which remained the most widely issued rifle of the war with nearly 20 million being produced.

Peter Suciu is a Michigan-based writer who has contributed to more than four dozen magazines, newspapers and websites. He regularly writes about military small arms, and is the author of several books on military headgear including A Gallery of Military Headdress, which is available on Amazon.com.