Seventy-five years ago this week, Major League Baseball owners and fans were assured the National Pastime would continue.

It was little more than a month after the Japanese pulled off a sneak attack at the naval base at Pearl Harbor. The war that had plagued Europe and Asia had come to the United States. Within a day, Congress had made a formal declaration of war, pulling the country into World War II.

During World War I, Secretary of War Newton Baker issued a “work or fight” order, saying that any able-bodied man should do one or the other. Major League Baseball cut its season short, ending on Labor Day (Baker, a former Cleveland mayor, later became a minority owner in his hometown team). Was something similar in the offing in World War II?

As it turned out, it wasn’t. On January 15, 1942, President Franklin Roosevelt wrote a letter to Baseball Commissioner Kenesaw Mountain Landis. The letter, which has become known as the “Green Light Letter,” was not an official dictate. Roosevelt said the decision rested with Landis and the owners, but “I honestly feel that it would be best for the country to keep baseball going. There will be fewer people unemployed and everybody will work longer hours and harder than ever before. And that means that they ought to have a chance for recreation and for taking their minds off their work even more than before.”

Roosevelt noted that any ballplayer who was fit for service should do so (Indians pitcher Bob Feller had already reported for duty in the U.S. Navy, having enlisted the day after Pearl Harbor, the first ballplayer to do so), and even if Major League Baseball relied on subpar talent, it will not dampen the popularity of the sport.

“If 300 teams use 5,000 or 6,000 players, these players are a definite recreational asset to at least 20,000,000 of their fellow citizens – and that in my judgment is thoroughly worthwhile.”

Coverage in the January 17, 1942, Plain Dealer said the owners would happily proceed. Roosevelt did have one request: More night games, so people working day shift could see them. Night baseball at the time was still a relative novelty.

Indians owner Alva Bradley was happily on board with the idea, saying he’d double the number of scheduled night games – all at Cleveland Stadium as League Park never installed lights – from seven to 14.

“It’s our duty to furnish relaxation for our fans, and if we can better carry out this program by playing 14 night games each season, efforts should be made to increase the schedule,” Bradley said. “With so many people working longer hours during the day, I believe there will be a greater demand for night baseball.”

The United States was at war for nearly four full baseball seasons, and the war affected all facets of life – including spectator sports. Many minor leagues suspended operations, unable to find enough men to field teams, and as Roosevelt predicted, the quality on the field of the major league product suffered. The St. Louis Browns won the 1944 pennant with their 4F team – 4F being the designation for men unfit for service. A total of 13 Browns players held that designation – the most in the Majors that year. The next year, the Browns included Pete Gray, an outfielder who had lost an arm in a childhood accident.

And it wasn’t just baseball. The Cleveland Rams of the NFL suspended operations for the 1943 season, and the Pittsburgh Steelers actually combined with other teams to have enough men to field a team – the Chicago Cardinals one year, and the Philadelphia Eagles another. High schools suspended football because they couldn’t find coaching staffs.

Finally, in 1945, World War II ended. Neither Landis nor Roosevelt lived to see the end of it. Landis took ill in the fall of 1944, missing the World Series between the Browns and the St. Louis Cardinals for the first time since becoming commissioner. He died that November. And Roosevelt died in April, less than a month before Germany surrendered. Three months later, Japan surrendered to end the war.

Baseball was getting back to normal – and night baseball, a novelty just five years earlier, was here to stay.