https://pjmedia.com/vodkapundit/d-day-by-the-numbers-by-the-men/
I want you to imagine picking up every resident of a medium-sized city, everything they’ll need to eat and drink and rest for a few days, any vehicles they might need, gasoline of course, plus lots of guns and ammo — did I mention this was a hunting trip? — and then moving them all in a few short hours a distance of anywhere from 30 to 125 miles or so.
Now imagine you have to move all those people and all that stuff partly by air, but mostly across heavy seas in foul weather.
Under enemy fire.
I should also mention that if you messed up any of the big details, a lot of your people are going to die, and then you’re going to have to figure out how to move them all back without getting too many more of them killed.
And all that is just the beginning. Because once you’ve done all that, those men on that “hunting trip” are going to have to take and widen a beachhead big enough and secure enough that you can rebuild (or build from scratch!) the ports and roads necessary to bring another million men over… plus all additional the stuff all those additional men will need.
That, in a logistical nutshell, was what the Allies had to accomplish 75 years ago on D-Day.
Supreme Commander, Allied Expeditionary Force, General Dwight Eisenhower said that “In preparing for battle I have always found that plans are useless, but planning is indispensable.” The planning which went into Operation Overlord boggles the mind.