What was D-Day?
Answer
The June 6, 1944 invasion of Normandy
Explanation
D-Day was the Allied invasion of Normandy on June 6, 1944, the largest seaborne assault in history and the moment that turned the tide of World War II in Western Europe. The operation, code-named Operation Overlord, was commanded by General Dwight D. Eisenhower as Supreme Allied Commander, with British General Bernard Montgomery in charge of ground forces. Planning had begun in 1943, and a sophisticated deception operation called Operation Fortitude, including dummy tanks and fake radio traffic in southeast England, convinced German commanders that the main assault would come at Calais rather than Normandy.
The Germans had built the Atlantic Wall, a chain of fortifications stretching from Norway to Spain, and Field Marshal Erwin Rommel commanded the defenses on the Normandy coast. The invasion was originally planned for June 5, 1944, but bad weather forced a 24-hour delay. Eisenhower made the final decision to launch on June 6 in the early morning hours of June 5.
About 156,000 Allied troops crossed the English Channel from southern England in roughly 5,000 ships, supported by 11,000 aircraft. American, British, and Canadian forces landed on five beaches in Normandy, France, code-named Utah, Omaha, Gold, Juno, and Sword. American troops faced the heaviest resistance at Omaha Beach, where soldiers of the 1st and 29th Infantry Divisions waded into withering machine gun fire from German bluffs and suffered roughly 2,000 casualties on that beach alone. American airborne troops of the 82nd and 101st Airborne Divisions parachuted behind enemy lines after midnight to seize bridges and crossroads.
By the end of June 6, all five beaches had been captured, and the Allies had a foothold in France. Total Allied casualties on D-Day were about 10,000, including 4,400 dead. German casualties are estimated at 4,000 to 9,000. By the end of June, more than 850,000 Allied troops had landed in Normandy.
Allied forces broke out of the bocage country in late July, liberated Paris on August 25, 1944, and pushed German forces back across France toward the Rhine. D-Day did not end the war, but it ensured Germany would be defeated, and it remains one of the most studied military operations in history.
Why this matters for your test
USCIS asks about D-Day because it represents the supreme example of American and Allied cooperation against fascism. The story is also a model of how democracies mobilize industrial capacity and citizen soldiers to defeat aggression abroad.
Source: USCIS 128 Civics Questions (2025)
