The recent death of George Kennan, at 101, reminded me of a small footnote in his long and brilliant career as a diplomat and foreign policy strategist. Mr. Kennan was a legend in U.S. foreign policy who served in several embassies, most notably in Moscow during and after World War II and was famous as the author of the “long telegram” in which he advised a more aggressive containment policy of the Soviet Union at the start of the Cold War. That memo had a huge influence on our policy over the next 40 years. What most people don’t know is that Kennan was also the head of our embassy in Berlin in December 1941 when the United States and Germany declared war on each other. It is also a fascinating lesson in how international law was still respected during the bloodiest conflagration in history and how it was simply tossed aside by Iran four decades later.

By the end of 1941, relations between Germany and the United States had deteriorated to the extent that the U.S. ambassador had already been brought back to Washington in protest over Germany’s invasions both east and west and the terror bombing of England. Kennan was the charge … the ranking diplomat who ran the U.S. Embassy in those nervous days as the world drifted toward its final lineup in the war. There were also a few U.S. nationals, mostly journalists, still in Berlin – the entire number of Americans was under 50. (CBS correspondent Howard K. Smith left Germany for Switzerland literally on the last train out … on December 6. He was en route as Japanese planes headed toward Pearl Harbor.)

I know about all of this because of an odd question I had one day 25 years ago. I lived in Washington during the Iranian hostage crisis and on my way to work every morning, I would pass the Iranian Embassy on Massachusetts Avenue. The embassy was closed by then. After the “students” took over our embassy in Tehran, President Carter deported all the Iranian diplomats and closed their embassy in protest. A lone D.C. police squad car stood watch over the place day and night. On my walk, I also passed the Japanese and German embassies and I got to wondering: What happened to those buildings during World War II? If the Iranians trampled all over diplomatic immunity and made a mockery of international law, what must have happened, I wondered, in the midst of a real war? Within two calls to the State Department, I found an old historian who gave me the entire story, which I found oddly anti-climactic. After the U.S. entered the war in December 1941, we simply gathered up all of the Germans, Japanese, and Italians. Our adversaries did the same with any Americans in their countries. And, in spite of the massive blood-letting that was unfolding, all groups were exchanged with the help of the Swiss. That should have ended my pursuit of a story except for an offhand thought from the historian. At the end of the conversation, he said, “Say, there’s going to be a reunion of all the people in the Berlin embassy in a few weeks … do you want to come?”

I did. And on a Saturday night in spring, I entered the formal dining room at the State Department to see a group of people obviously delighted to see each other after all these years. After the passage of time there were only jovial recollections of their time together. The whole thing reminded me of a college reunion. Everyone was excited when one of them arrived with a carved bat and a ball fashioned out of string that was used to play baseball. The youngest man in the group, who seemed out of place and was the only child there at the time, talked about throwing snowballs at the German guards, giving a “Hogan’s Heroes” take on the events. But it was their leader, George Kennan, who reminded everyone of the realities of the situation.

As it turns out, the U.S. government gathered all of the Germans, Japanese, and Italians and placed them under guard at the Greenbrier Hotel in White Sulphur Springs, W.Va., one of the great luxury hotels in North America. (After the exchange, the Army took over the hotel and converted it into a massive hospital and surgical theater that accommodated over 24,000 wounded soldiers.) The Germans followed suit and placed the Americans in a hotel outside of Berlin. The only trouble was that it was a “summer” resort and there was no heat. The Germans and United States declared war on each other four days after Pearl Harbor and from early December throughout that cold winter of 1942, the Americans froze.

It was Kennan who remembered the difficulties that the group encountered. As he addressed his former colleagues, he spoke honestly about the depressions that set in – how he felt so miserable and cold some days, he couldn’t even leave his room to go down to the dining room. But he also spoke of pride and admiration for the group gathered in front of him. With misty eyes and a halt in his speech, he remembered that in spite of the “difficulties,” there was a spirit of optimism that still impressed him 40 years later – whether it was fashioning that baseball out of string, or forming classes on everything from music to art history to help pass the time, this small band of Americans gave him the courage to keep going. Looking at the faces of the people as he spoke, it was obvious that they felt the same way about him.

This scene would unfold countless times over the next four years. Americans, whom Hitler thought too pampered and spoiled to fight a war, found themselves in utterly miserable conditions far from home. More often than not, they faced it all with purpose, drive, and a unique sense of humor. The small group of Americans under George Kennan in Berlin set the standard for what was to come … as it still does today, in places named Basra, Kandahar, and Tora Bora. And like Ambassador Kennan, I also marvel at that spirit and sense of duty.

Mr. Kozak is the author of “The Rabbi of 84th Street” (HarperCollins).