On the night of June 5th, 1944 more than 156,000 troops from the United Kingdom, United States, and Canada (a contingent of the “Allied Forces”) were amassed along the English coast waiting for their orders. They were about to embark on the largest seaborne invasion in history. Their mission was to cross a 100-mile wide part of the English Channel at night and assault a highly fortified enemy position at Normandy, located on the northern shores of France.

They were up against 50,000 Nazi troops (protected by bunkers), 170 artillery guns, anti-tank obstacles, barbed wire, booby traps, and 4 million landmines, spread across 50-miles (80 km) of coastal area. The enemy also had at its disposal 800 aircraft, 300 tanks, 3 torpedo boats, 29 fast attack craft, and several U-boat submarines. It was a formidable defensive position. One which the Allied Forces would attempt to overrun with virtually no cover or concealment.

Adding to the complexity and danger of the mission was poor weather conditions. The Allies had a window of opportunity of only two days, otherwise they’d have to wait a month for the next opportunity (because of tides). On the first day an unexpected storm arose. As a result, General Dwight D. Eisenhower, Supreme Commander of the Allied Forces, decided to delay the mission for 24 hours to let the weather conditions improve. Though conditions were better the next day, the weather was still poor. High winds and cloudy conditions presented obstacles for both the landing crafts and the 24,000 paratroopers that would be dropped in behind enemy lines, potentially putting them off course.

I’ve heard it said before that the Allies were taking a big risk by attempting to invade Normandy. On the surface it does seem like they were, given how strong the German defensive position was and the sheer number of troops involved in the assault. But I contend that the Allies were taking an appropriate amount of risk. Battle is always risky for those involved, and it’s not fun to think about human lives in terms of mere numbers, but to a certain extent that’s the way political and military leaders need to think in order to save lives. If you don’t put those 180,000 lives on the line (plus French civilian casualties of 20,000 to 50,000), how many other people will die? From 1939 to 1945 the war claimed over 70-million lives. How many more people would have died if the Allies had not attempted the Normandy invasion?

Also, the Allies lowered the risk by doing two things:

1) They prepared. They spent a year planning, training, and building up resources. They also ran a campaign of misinformation to make the Nazi’s think the attack point would be somewhere else and on a different day. And in addition to the 156,000 that would land on the beaches and the 24,000 paratroopers going in behind enemy lines to secure roads and bridges, they brought with them 1,000 tanks, 4500 bombers, 3800 fighters planes, and 200 warships (not including escort ships, landing craft, etc.). Allied bombers, battleships, cruisers and destroyers bombarded the coastline for hours before any troops set foot on the beaches.

2) They didn’t risk more than they could afford to lose. Imagine if all 180,000 troops involved in the invasion had died. That would have been a devastating loss of life and manpower, and likely would have had a negative psychological effect on the remaining Allied troops. However, though the battle would have been lost, and the cost high, the Allies still would have had at least 3 million troops left to help win the war. They risked less 5% of their total manpower on D-Day. There were also 195,000 naval personal involved, but they weren’t nearly as exposed as the ground troops. But let’s say that all 180,000 ground troops and half of the naval personnel had been killed, bringing the total number of dead to around 280,000, that’s still no more than 10% of total manpower lost. And the chances of that many people being killed wasn’t high, given all the preparation that went into the invasion, weakening of the German defenses from bombardment, and greatly outnumbering the enemy at Normandy in troops, planes, tanks, and ships.

Millions of troops were waiting in England for the results of the initial assault. They weren’t put at risk until after the initial 180,000 troops were successful in overrun the German defences at Normandy. After that, it made all the sense in the world to send those reinforcements in to help take back France and eventually enter Germany. Which they did, in less than a year.

What about potential equipment loses?

The Allies had approximately 120,000 tanks, but sent only 1,000 on D-Day. They had approximately 100,000 bombers and fighter planes, but deployed only 8,000 on D-Day. And they had approximately 700 warships, but used no more than 200 of them on D-Day. In other words, the Allies had an arsenal of over 220,000 tanks, bombers, fighter planes, battleships, cruisers, and destroyers, but risked losing only 9,000 of them (representing less than 5% of what they had).

The mission was not without risk. But the Allies risked a relatively small percentage of what they had to do something that could help end the war sooner, saving many more lives, and if they failed they would still have plenty of resources left. In comparison, it was much less risky than what Hitler did by invading the Soviet Union. Hitler lost over 1-million troops in that failed expedition, following in the footsteps of another fool, Napoleon, who also failed in his attempt to invade Russia a century prior.

Plans for the Normandy invasion were discussed between British Prime Minister Winston Churchill and U.S. President Franklin D. Roosevelt for a year before the mission was carried out. It was ultimately their decision, but the plan wasn’t developed by them alone. Military leaders were involved, including Britain’s Field Marshal Montgomery, and General Eisenhower, who oversaw the mission. When Eisenhower was going through officer training at West Point he was a shrewd Poker player. He was the best player among his officer candidate classmates, who lost substantial sums of money to him, causing him to eventually stop playing, to avoid their resentment. One time he mentioned to someone that he was amazed at how little his classmates understood probability. I have to imagine that Eisenhower’s probabilistic thinking ability, going back to his Poker playing days (and later, his Bridge playing days), played a role in how the D-Day mission was planned and executed.

The Allies didn’t risk everything they had. Not even close. They risked a relatively small percentage of what they had on a mission that had a reasonably good chance of succeeding. And that’s exactly how good Poker players play Poker. In Poker you have what’s known as your “bankroll”. That’s all the money you have in the world for playing Poker. But you don’t use it all at once. You only use a certain percentage of it to “buy in” to a game. The buy in money is the max amount you’ll be able to risk. If you lose that money, you can “buy in” again using money from your bankroll. But only if you choose to. Even when a player goes “all in” they’re only going all in with the chips they’re using for that game, not their entire bankroll.

In terms of the Allied Forces at the time of the invasion of Normandy, their “bank roll” was 3,000,000 troops (again, not fun to think about people this way, but it’s reality) and 220,000 tanks, bombers, fighter planes, and warships. And their “buy in” amount was the 180,000 troops, 195,000 naval personnel, and 9,500 tanks, bombers, fighter planes, and warships they sent on D-DAY.

In Poker, unless you’re bluffing, you wait until you have great cards before you make a big bet. In the case of the Allies, bluffing wasn’t an option at Normandy (though they did run decoys to make the enemy think they were going to attack at a different location and date), they either had the resources to defeat their opponent or they didn’t. In hindsight, it’s clear that they did, as their causalities amounted to approximately 10,000 (4,400 dead), and the loss of 3 warships, 100 bombers and fighter planes, and 200 tanks.

Eisenhower and others ran the numbers beforehand and decided that they had superior cards and appropriately made a big bet, but not so big that they’d be bankrupt if they were wrong.

P.S. All numbers mentioned are approximate, as it was difficult to find precise numbers on this. Also, many more troops and equipment were used to take back France than mentioned in this article. Causalities for the Allies numbered in the hundreds of thousands by August of 1944, and there were many more after that. Any attempt to invade Nazi held territory, including France, was going to result in large losses, but an invasion of some kind needed to take place. The question is whether the entry point at Normandy was too risky, in terms of attempting to penetrate that particular defensive position along the northern coastline. This was also not a question of whether another entry point might have been less risky. The “soft underbelly” approach through southern Italy, which Churchill wanted, might possibly have been better.