June 6 marks the 70th anniversary of the battle for the beginning of the end of a Nazi-dominated Europe.

In the annals of history, the invasion of Normandy is recalled as one of the great military victories. At the time, in the long hours of the longest day, while airborne troops leaped into the darkened skies behind the coastline and waves of troops crossed to shore and stormed the beaches, victory seemed anything but assured.

The day before, Gen. Dwight Eisenhower, the supreme commander of the invasion, fretted over the weather conditions. Adverse surf conditions could botch the whole operation. The forecast was “iffy.” Ike declared with determination, “Ok. Let’s go.”

Eisenhower was far from confident. In the early hours, while the airborne troops fought in desperate battles behind the hedgerows and the troops hunkered down seasick in the their landing craft and headed for shore, he retained a letter to the Army Chief of Staff he had penned two days earlier, taking personal responsibility if everything went wrong. “If any blame or fault is attached to the attempt,” Ike wrote, “it is mine alone.”

Virtually nothing went exactly as planned on D-Day. The British and Canadians struggled to secure their beaches. The bombers missed their targets. So did the Navy’s guns firing at the German fortifications. The 4th Infantry Division landed in the wrong place at Utah Beach. Army Rangers couldn’t find the enemy’s coastal guns they’d been sent to seize.

The airborne troops were scattered all over the countryside. Worst of all was “bloody” Omaha Beach. The generals sent tanks and artillery to blast through the German beach defenses. They sank. The Germans were more numerous and far tougher fighters than intelligence had predicted. At one point, Gen. Omar Bradley, who was overseeing the landings, thought he might have to pull the U.S. troops off the beach before they were all slaughtered.

Omaha Beach was the linchpin of the invasion: If it failed, the entire operation might have had to be scrapped.

In the end, the boys fought their way off the beach. History had its victory.

If there is one lesson from the longest day, it was probably best captured in these words from Eisenhower: “History does not long entrust freedom to the weak or the timid.”

D-Day offers an enduring lesson for all democracies. Equal measures of courage, confidence, prudence, and judgment were the right mix for winning on D-Day. It is the best formula for fighting for freedom—every day.