That’s because it motivated the United States—then only tangentially involved in the conflict—to become a full-fledged enemy of the Axis powers.
Although the U.S. was not in a state of war during the surprise attack on its naval base at Pearl Harbor, Hawaii (then a U.S. territory), Pearl Harbor is one of the most consequential “battles” of World War II. That’s because it motivated the United States—then only tangentially involved in the conflict—to become a full-fledged enemy of the Axis powers.