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D-Day

D-Day usually refers to 6 June 1944, the first day of the Allied invasion of Normandy in Nazi-occupied France during the Second World War.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

D-Day usually refers to 6 June 1944, the first day of the Allied invasion of Normandy in Nazi-occupied France during the Second World War. It was the opening phase of Operation Overlord and is widely regarded as one of the most important military operations of the war.

Background

D-Day was planned as part of Operation Overlord, the Allied campaign to open a western front in Europe against Nazi Germany. Weather delays pushed the invasion from 5 June to 6 June 1944.

The invasion

On 6 June 1944, Allied forces landed along the Normandy coast in a combined naval, air, and land assault. The beaches were assigned the code names Utah, Omaha, Gold, Juno, and Sword. Canadian troops landed at Juno Beach as part of the Allied forces.

Scale and casualties

The operation involved thousands of ships and aircraft and tens of thousands of troops on the first day. Source estimates vary, but the invasion was extraordinarily costly, with significant Allied casualties on 6 June 1944. Approximately 156,000 to 160,000 Allied troops landed on the first day.

Historical significance

The landings established the Allies in northwest Europe and became a turning point in the campaign against Nazi Germany. D-Day is often described as the beginning of the end of the war in Europe.

Key facts

  • D-Day was the Allied invasion of Normandy on 6 June 1944.
  • The operation was codenamed Operation Overlord.
  • Allied troops landed on five beaches in Normandy: Utah, Omaha, Gold, Juno, and Sword.
  • The invasion involved land, air, and sea forces and is described as the largest amphibious invasion in military history.
  • Canada was one of the Allied countries involved, with Canadian troops landing at Juno Beach.
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Canadian context

Canadian troops took part in the Normandy landings and landed at Juno Beach, making D-Day an important event in Canadian military history and remembrance.[6][11][13]

Frequently asked questions

What does D-Day mean?
In military usage, D-Day is the term for the first day of an operation; in this context, it refers specifically to 6 June 1944.
What happened on D-Day?
Allied forces landed on the beaches of Normandy, France, in a large amphibious assault against Nazi German defenses.
What was the codename for D-Day?
The invasion was part of Operation Overlord, with the beach landings also associated with Operation Neptune in some sources.
Which countries took part?
The main Allied forces included the United States, the British Commonwealth, and Canada, alongside other Allied nations.
Why is D-Day important?
It opened a Western Allied front in Europe, helped secure a foothold in France, and contributed to the eventual defeat of Nazi Germany.

References

  1. Dwight D. Eisenhower Presidential Library — https://www.eisenhowerlibrary.gov/research/online-documents/world-war-ii-d-day-invasion-normandy
    Supports: Date, Operation Overlord, beach code names, scale of invasion, and overall significance.
  2. U.S. Army — https://www.army.mil/d-day/
    Supports: Date, troop numbers, Allied forces, and common explanations of the term D-Day.
  3. U.S. Coast Guard History — https://www.history.uscg.mil/Browse-by-Topic/Conflicts/World-War-II/D-Day-June-6-1944-Normandy/
    Supports: Allied participants, operation codename, and invasion timing.
  4. The National WWII Museum — https://www.nationalww2museum.org/media/press-releases/d-day-fact-sheet-0
    Supports: Invasion date, beach names, and scale of landings and supply buildup.
  5. HISTORY — https://www.history.com/articles/d-day
    Supports: General overview of the Normandy landings, involved countries, and broader wartime significance.
  6. BBC News — https://www.bbc.com/news/world-48513108
    Supports: Date, participating countries including Canada, beach names, and the meaning of D-Day.
  7. United States Holocaust Memorial Museum — https://encyclopedia.ushmm.org/content/en/article/d-day
    Supports: Date, Operation Overlord, and Allied troop participation.
  8. Encyclopaedia Britannica — https://www.britannica.com/event/Normandy-Invasion
    Supports: Normandy Invasion context, date, and historical significance.