June 6, 2017–In these dark days when we need to remind ourselves that, yes, there truly are common interests among nations, and goals for which all are willing to strive, it is good to have history. One shining example of common action took place seventy-three years ago today. Of course, I am referring to D-Day, the “Longest Day,” the Allied invasion of Normandy, beginning the northwest Europe campaign that marked the final stage of World War II in the west.

There were 70,500 American troops plus 83,115 British and Canadian, and 600 0r so French. Roughly 23,000 of these troops arrived by parachute or glider. The armies were supported by 11,000 aircraft sorties and 5,000 naval vessels. Among this armada were warships or aircraft from the U.S., U.K., Canada, France, Norway, and Poland; reserve troops from Czechoslovakia, Belgium, and Holland; resistance forces in France and the Low Countries; plus more. You can see almost the entire line up of what later emerged as the North Atlantic Treaty Organization (NATO). The main country missing from the list would be Germany–and they, in World War II, were the enemy.

The invasion of June 6, 1944 led to fierce fighting. Americans will always think of the battle on Omaha Beach and the bitter field-to-field struggles for Normandy’s bocage country. Our British Commonwealth brothers will forever honor those who fought in the repeated fights over the city of Caen. The Germans will long remember their failed effort to seal up the Normandy bridgehead, the Allies’ breakout, and the battle for the Falaise Gap (for a detailed look at the struggle that followed D-Day read my book Normandy Crucible ).

It is a measure of the strength of our united purposes that wartime enemies became friends afterwards, and that the NATO alliance and that the union has evolved into a mainstay of American foreign policy. On this day let us all remember that.