How D-Day balanced British and American weight

Was D-Day primarily a British or an American operation?

It was a coalition operation: British capabilities weighed heavily on D-Day, while American material support and later troop flow shaped the campaign's command structure.

The landing-day personnel mix is described as broadly balanced, with British weight in shipping, landing craft, and air support, followed by a growing American and Commonwealth contribution ashore. Eisenhower's leadership reflected the expected scale of American material support. British senior subordinates reflected the forces immediately committed on D-Day itself.