Why did Allies choose June sixth?

Answer 1

The Allied landing troops needed a low tide to see and avoid underwater mines and obstacles. The need for a low tide on the channel, determined by the moon's tug on the Atlantic, narrowed the choice of invasion dates in June. Conditions would be right on just 6 days that month -- June 5 to 7 and June 19 to 21. Only once a month does a low tide at dawn coincide with a bright moon. That June, a full moon at low tide would occur on the sixth. The invasion could thus take place on June 5, 6, or 7. Eisenhower chose June 5. But there was a storm before and after the June 6th, so the June 6th was the only window of opportunity when the weather would clear, if only for 36 hours: if not landed on that day, the operation would have to be postponed. Thereafore the D-day was postponed for one day, on 6th. Allies actually caught a lucky break on that day: because of the Allied air supremacy Germans were not able to monitor the weather above the Channel and were not aware that the storm would lay low for few days: most of the German troops were not on alert and even Rommel went to Germay. There was also a political motivation. The Allies were being pressured by Russia to begin a 2nd front in France in order to pull some German divisions away from those fighting against them. The Allies had to push back the date due to lack landing craft that had been in the Mediterranean area in support of the Anzio beach in Italy. There were many strategic factors that contributed to the date being set for this time of the year.

Answer 2

Full moon, low tide, June 4 and 5 it rain pretty much the whole day and cleared up on June 6,1944.

Answer 3

Eisenhower chose the 5th of June, but a storm in the English Channel forced a postponement of one day.