Dec. 7, 1941, like Sept. 11, 2001 and the month of August 1914, is a time that continues to live in historical infamy. It provides a temporal dividing line between the American isolationism that preceded it and the American engagement with the rest of the world that followed. This engagement, for better or worse, endures in the 21st century.

The great English historian Edward Gibbon described history as being “little more than the register of the crimes, follies and misfortunes of mankind.” The Japanese attack on Pearl Harbor, which caused the deaths of over 2,400 Americans, was certainly a crime that galvanized and unified our nation. It also set into motion a series of misfortunes that would culminate with mushroom clouds over Hiroshima and Nagasaki less than four years later.

The attack was surely a great folly as well. As Admiral Yamamoto presciently remarked, “I fear all we have done is to awaken a sleeping giant and fill him with a terrible resolve.” World War II was remarkable among American wars in many ways, but not least because of the political unanimity that followed Pearl Harbor. All races, creeds and political viewpoints were united to remember and avenge the attack. President Franklin D. Roosevelt led our nation in the construction of a vast “Arsenal of Democracy” that ground the Axis powers into dust.

Every year at this time, charges arise that FDR knew in advance of the attack on Pearl Harbor. We live in an age of rampant conspiracy theorizing with fires stoked by Internet speculation, yet for more than 70 years, these charges have lacked credible evidence. Yes, FDR knew in a general sense the Japanese might launch an attack on American military positions throughout the Pacific, but he did not know the naval base in Hawaii would be targeted the early morning of Dec. 7. FDR, having served as assistant secretary of the Navy during World War I, loved the U.S. Navy above all other military branches, and he would have done anything in his power to preserve it from destruction.

FDR was not a perfect wartime leader. He trusted Stalin too much. He was overly suspicious of de Gaulle. He was excessively partisan when he declined Herbert Hoover’s offer to assist with humanitarian relief. But he was an inspirational leader who led his nation to victory in World War II. And he was certainly not a traitor.

These charges against FDR are based upon a gross underestimating of Japanese abilities. The Japanese Navy really did achieve strategic surprise against the Americans. They did so mainly because Admiral Nagumo ordered the fleet to maintain strict radio silence for its voyage from Japan to the Hawaiian Islands: “All transmissions of messages are strictly forbidden.”

Many Americans simply could not credit the Japanese with such military skill. Even after Pearl Harbor, some suggested the pilots of attacking planes marked with the Rising Sun must have been German!

Such disbelief in the abilities of members of other cultures and races to inflict harm on the United States was not without precedent. When news of the Battle of Little Bighorn first spread in 1876, many Americans could not accept that Custer’s 7th Cavalry had been wiped out in Montana by a force of Native Americans.

Similarly, after more than 2,900 people were killed on Sept. 11, 2011, some alleged that 19 hijackers, most from Saudi Arabia, could not have inflicted the damage caused that day.

While history may be the record of mankind’s crimes and follies, it also holds valuable lessons. One lesson of Dec. 7 is that one should never underestimate an opponent based on ethnic stereotypes. Put another way, the only cure for racism is knowledge.

Christopher Kelly is the co-author of “America Invades: How We’ve Invaded or Been Militarily Involved with almost Every Country on Earth” and “Italy Invades: How Italians Conquered the World.”