It’s December 7, a momentous date in history. I think back to what this date meant to a U.S. civilian population rocked by the Japanese surprise attack, and I think about those already serving in the military on Dec. 7, and what a declaration of war meant to them. As you know, the draft had begun, and thousands of 12-month draftees knew as soon as bombs fell at Pearl that their number was truly up, and they wouldn’t get out after just a year. But they would soon be joined by millions of enlistees outraged by what happened to the Pacific fleet and by Hitler’s declaration of war on the United States.

Hollywood’s beloved boy-next-door movie star Jimmy Stewart was one of those draftees and had entered the service in February 1941. As described in my book Mission: Jimmy Stewart and the Fight for Europe, he was, as of Dec. 7, Corporal James Stewart, and in less that a month he would earn his wings as an Army flier with the rank of second lieutenant. (If you’re a WWII history lover, please explore this January 18 auction of an incredible military aviation collection in Plymouth, MA, which includes a complete Norden bombsight, pilot’s wings, very pistols, uniforms, plane parts, books, and so much more.)

The Mission hardcover gets a fair amount of attention at this time of year. Right now it’s being featured in all Barnes & Noble locations across the U.S., face out in the Military History section. Mission describes all 20 combat missions flown by Stewart, some of them “milk runs” over the coast of France, but many others harrowing, seven- and eight-hour flights that took Jim deep into Germany for strikes at the industrial heart of the Reich on the run-up to D-Day.

Of course there’s another reason why a book about Jimmy Stewart and the war does well at the holidays; the first picture he made after the war, while still suffering PTSD from all those missions, was It’s a Wonderful Life. When he began making this one in the spring of 1946, life wasn’t so wonderful for James Maitland Stewart. He’d left the holy crusade against Hitler, which had been Jim’s great purpose in life. His mind had been shattered by a few missions too many and the relentless strain of command, necessitating visits to the “flak farm” to de-stress. He’d aged in the service and no longer felt he could land a job as a romantic idol. And in fact no studios came calling except Frank Capra with his risky idea for a picture about a suicidal man and an angel.

Suffering nightmares and flashbacks, his hands shaking, his diet shot from anxiety and confidence gone due to the years-long break from moviemaking, Jim stepped onto RKO soundstages to begin this crazy picture with Capra. And the director, who had been a king of 1930s Hollywood, was battling his own demons. He’d been away doing war work too, and now a grittier Hollywood had emerged that rejected his notions about crafting sentimental pictures. There was this film noir thing that now suited a shell-shocked, post-war America. Nobody welcomed Capra back just like nobody had welcomed Stewart—“welcomed” as in offered work. The men were desperate, as noted by IAWL leading lady Donna Reed, who described Capra and Stewart on the set as tense second-guessers; it wasn’t the happy shoot you’d imagine as these two giants of pre-war cinema set about trying to reestablish themselves in a younger, reborn Hollywood that had passed them by.

I was neutral on Stewart when I began writing Mission, and he’s a tough character to know because he closed himself off in some regards. But he showed remarkable bravery in the war, and even more guts in the peace that followed, because he did nothing short of win the battle of Hollywood; this 38 year old with the shakes who looked 50 began a second career when the wags called him washed up. First, he used the darkness of war in his characters, many of whom were now haunted or seeking revenge. Second, he urged producers to gamble on him as he gambled on himself—he’d take a smaller salary upfront in exchange for a percentage of the profits on each picture.

In It’s a Wonderful Life, George Bailey is called “the richest man in town” for having friends. But in the 10 years after the war, Jim Stewart became the richest man in town for picking good pictures and banking a fortune in profit participation. By any measure this was a hero, and it’s fitting that every year we get around to celebrating him and the post-war venture of two down-and-out war veterans, which happened to become the most beloved movie in Hollywood history.