As never before, the engines of war — on the ground, on the sea, in the air — ran on a river of oil. Indeed, the need to conserve fuel was a driving force behind the German invention of the Blitzkrieg, or "lightning war." The strategy allowed the Germans to fight fierce, but short battles that led to decisive victories before fuel ran out.

Why did Hitler launch the Second Front on July 22, 1941 — a disastrous mistake — despite his alliance with Stalin, and much to the consternation of his generals? He'd set his sights on the Russian oil fields at Baku.

In north Africa, the objective was the same: strike into the Middle East through Egypt to seize the richest oil reserves in the world. General Rommel, Hitler's "Desert Fox," almost succeeded, but when he reached the outskirts of Cairo in 1942, he ran out of fuel — the precious resource he had been sent to capture.

In Asia, the story was much the same. As Tojo's troops marched into Manchuria, it was only a matter of time before the oil fields to the south would become their primary target: in Malaya, the Dutch East Indies and Indochina. America's first response to the Japanese juggernaut was to embargo shipments of aviation gasoline to Japan.

To better protect the area, the U.S. moved its Pacific Fleet from southern California to a Hawaiian naval base called Pearl Harbor. Most Americans were unaware of Japan's pursuit of oil reserves in the Pacific or their country's token response.