Chicago was warm on December 7, 1941—warm for December, with a high of 39 degrees. It was Sunday. With the stores closed, people had a chance to take the day off from Christmas shopping. Maybe they were headed out to Comiskey Park to watch the Cardinals battle the Bears.

The news hit the city shortly after noon. The Japanese had attacked Pearl Harbor.

Pearl Harbor—where’s that? And Chicagoans searched their maps, and found it was in Hawaii, and realized that their country was now at war.

Little more than a year ago, 40,000 people had gathered in Grant Park to hear Charles Lindbergh tell them that the U.S. must stay out of foreign wars. The Tribune had been sounding the same message. But things were different now. We had been attacked. We would stand together as Americans.

Suddenly, all Chicago was in motion. Sunday afternoon looked like Friday evening rush hour. Municipal Airport and the city’s six railroad terminals were jammed with travelers whose plans had abruptly changed—soldiers and sailors returning to their units, politicians on their way to Washington, private citizens just wanting to get back home. There were crowds gathering at the churches, too.

People hauled out American flags and hung them on their porches. Neighbors who hadn’t spoken in years exchanged greetings. Newspapers printed extra editions, and they were immediately scooped up. The Chicago Sun, which had begun publishing only three days earlier, sold out its entire run. Everyone wondered what would happen next.

On Madison Street, four windows were smashed at the Oriental Trading Company. Other than that, no violence against local Japanese was reported. At the Japanese Consulate, employees were seen burning records.

Mayor Edward Kelly announced the police and fire departments would receive training on how to prevent sabotage. The mayor also said he’d ask the city council for money to hire more public safety personnel. “Those godless gangsters have stopped  their bluffing to start their bombing,” he thundered. We had to be ready for anything.

Already lines were forming at military recruiting offices. The country needed men for the coming fight. At the Warren Avenue police station, an army deserter from Texas turned himself in. “I want to go back and do my part,” he said.

Chicago was at war. It would not know peace for 1,351 days.