July 28, 1941. Japanese troops march into the southern half of French Indochina, and though barely a shot is fired, this is one of the most fateful days of the entire war. This is the move that puts Japan and the United States on the road to Pearl Harbor, and the trigger is oil.
Here is the trap Japan had built for itself. It had been at war in China for years, bogged down, and its whole war machine, the navy, the air forces, the army, ran on oil that Japan did not have. It imported the overwhelming majority of its oil, and most of that came from the United States. So Japan was fighting a war of conquest while its fuel tank was held by the country most opposed to that conquest. Everyone in Tokyo knew this was the noose around their neck.
Their answer was to look south, to the oil rich Dutch East Indies, today's Indonesia, and the rubber and tin of British Malaya. To reach them, Japan needed bases, and French Indochina, whose colonial masters had been beaten by Germany the year before and could not resist, was the stepping stone. Japan had already moved into the north. On this day it took the south too, putting its airfields and ports within striking range of Malaya, Singapore, and the Indies.
Washington's response was immediate and, in effect, an ultimatum. Roosevelt had already frozen Japanese assets in the United States days earlier, and now, with Britain and the Dutch joining in, the flow of oil to Japan was choked off almost entirely. The embargo was total. It was meant to make Japan back down.
It did the opposite, and this is the awful logic of it. Japan now had maybe a year or two of oil stockpiled and then its war machine would grind to a halt. Its leaders felt they had only two choices. Give up their empire and their war in China to get the oil turned back on, a humiliation the military would never accept. Or seize the oil of the Indies by force, which meant war with Britain and the Netherlands, which meant war with the United States and its fleet at Pearl Harbor.
They chose war. Everything from here, the planning for the carrier strike, the final failed negotiations, the attack on December 7, flows out of the box that was closed on this day. When Japan walked into southern Indochina and America turned off the oil, the countdown to Pearl Harbor had, in effect, already started. Four and a half months later the bombs fell on Hawaii, and the road to them ran straight back through this date.