A few mornings ago I looked out the window to see my balcony of mostly tropical plants shivering under a blanket of . . . snow. While December snow wouldn’t be a surprise elsewhere, here in Houston it was unusual enough to make headlines and a big splash on Facebook.

One morning three quarters of a century ago, songwriter Irving Berlin looked out the window and was as surprised as to see snow. He was staying in a cabin in Banning, California, not too far from where the Southern California wildfires are raging now. Inspired by the unexpected dusting, he wrote the song “White Christmas” at the very beginning of the fateful year 1940. (Berlin commonly wrote a song a day. How’s that for being a productive writer?)

Christmas-themed songs and liturgical settings have been around since at least as far back as the 4th Century when Christmas Day was fixed as the 25th day of December. But our modern Christmas carols don’t have a 4th-Century air. In fact, they evoke the 1940s. Why is this?

The music record business had taken a severe drubbing during the Depression but was rapidly recovering on the eve of the United States’ entry into World War II. From 1938 to 1941, record sales more than tripled as more and more workers found lucrative defense-related jobs. At the same time, here as in most developed nations, the power brokers had initially supported Hitler and Mussolini. (Both dictators were adamantly opposed to both trade unions and communism, the twin bugaboos of generations of businessmen.) When this stance abruptly became passé it became necessary to unify the American people so as to enable the economy to negotiate this sudden reversal. An appeal to nostalgia and a harkening back to a mythical national Golden Age was called for. In 1940 the cultural and population center of gravity of the United States was still located near New England, and “White Christmas” brilliantly celebrates the New England winter as few other songs before or since have done.

This isn’t to say that all Christmas carols were deliberately integrated into the war effort; but the newly written carols, the ones we still hear today when we’re out shopping in the mall, suited the new public mood almost perfectly—and so even today they’re fondly, if perhaps unconsciously, reminiscent of a time of national unity.

The carol that captures the wartime experiences of Americans better than all the rest is “I’ll be Home for Christmas,” recorded late in 1943, near the nadir of the campaign in the European theater. The lyrics were  from the point of view of a homesick GI who promises his family he’ll be home for Christmas, “if only in my dreams.” This song was at the time considered to be such an effective morale booster that thousands of discs were distributed all over the world by the US military (though, curiously enough, not by the British military establishment, which feared the same song could actually depress morale.)

The abrupt philosophical U-turn to enter the war and to oppose Fascism, the meteoric rise in music record sales, the suddenly booming economy as the nation geared up for war, and the melancholy separations brought on by the war all combined to make the new Christmas carols of the 1940s resonate with the national consciousness, then and even now.

And in a real-life example of the Biblical exhortation to beat swords into plowshares, the technology developed to accurately record and play back the sounds of U-boats plying their deadly trade connected with a mass market soon after the war—in the form of “high-fidelity” amplifiers with which to listen to those Christmas carol records.