When we look back across history, it’s all too easy to assume that because something happened, it had to happen exactly the way it did.

But there was nothing inevitable, for example, about Napoleon’s defeat at Waterloo or the Union’s victory at Gettysburg. These battles could easily have turned in a different direction, and the tide of human history might have changed with them.

The same is true for D-Day, June 6, 1944, when Allied forces began carrying out the largest amphibious invasion in history. Within a year, the Allies succeeded in freeing Europe from Nazi domination.

But nobody knew what the outcome would be when the mission started. Just in case, commanding General Dwight D. Eisenhower drafted a brief letter stating:

Our landings in the Cherbourg-Harve area have failed to gain a satisfactory foothold and I have withdrawn the troops. My decision to attack at this time and place was based upon the best information available. The troops, the air and the Navy did all that bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone.

He never had to release that note.

At the White House, President Franklin Roosevelt also knew that the mission might not succeed. That evening he took to the airways to encourage Americans to pray for the success of the invasion.

As Americans remember D-Day 68 years later, it’s fitting that we also remember FDR’s moving prayer. Here’s one way to do so: The World War II Memorial “commemorates the sacrifice and celebrates the victory of ‘the greatest generation,’” as the National Park Service notes.

Earlier this year, the House of Representatives passed H.R. 2070, “To direct the Secretary of the Interior to install in the area of the World War II Memorial in the District of Columbia a suitable plaque or an inscription with the words that President Franklin D. Roosevelt prayed with the nation on June 6, 1944.”

FDR’s prayer, calling upon God to bless America’s mission in Europe, deserves a prominent place at the World War II Memorial. The entire prayer, with its powerful appeal to God and its emphasis on the goodness of America’s fight, follows:

My Fellow Americans:

Last night, when I spoke with you about the fall of Rome, I knew at that moment that troops of the United States and our Allies were crossing the Channel in another and greater operation. It has come to pass with success thus far.

And so, in this poignant hour, I ask you to join with me in prayer:

Almighty God: Our sons, pride of our nation, this day have set upon a mighty endeavor, a struggle to preserve our Republic, our religion, and our civilization, and to set free a suffering humanity.

Lead them straight and true; give strength to their arms, stoutness to their hearts, steadfastness in their faith.

They will need Thy blessings. Their road will be long and hard. For the enemy is strong. He may hurl back our forces. Success may not come with rushing speed, but we shall return again and again; and we know that by Thy grace, and by the righteousness of our cause, our sons will triumph.

They will be sore tried, by night and by day, without rest—until the victory is won. The darkness will be rent by noise and flame. Men’s souls will be shaken with the violence of war.

For these men are lately drawn from the ways of peace. They fight not for the lust of conquest. They fight to end conquest. They fight to liberate. They fight to let justice arise, and tolerance and goodwill among all Thy people. They yearn but for the end of battle, for their return to the haven of home.

Some will never return. Embrace these, Father, and receive them, Thy heroic servants, into Thy kingdom.

And for us at home—fathers, mothers, children, wives, sisters, and brothers of brave men overseas, whose thoughts and prayers are ever with them—help us, Almighty God, to rededicate ourselves in renewed faith in Thee in this hour of great sacrifice.

Many people have urged that I call the nation into a single day of special prayer. But because the road is long and the desire is great, I ask that our people devote themselves in a continuance of prayer. As we rise to each new day, and again when each day is spent, let words of prayer be on our lips, invoking Thy help to our efforts.

Give us strength, too—strength in our daily tasks, to redouble the contributions we make in the physical and the material support of our armed forces.

And let our hearts be stout, to wait out the long travail, to bear sorrows that may come, to impart our courage unto our sons wheresoever they may be.

And, O Lord, give us faith. Give us faith in Thee; faith in our sons; faith in each other; faith in our united crusade. Let not the keeness of our spirit ever be dulled. Let not the impacts of temporary events, of temporal matters of but fleeting moment—let not these deter us in our unconquerable purpose.

With Thy blessing, we shall prevail over the unholy forces of our enemy. Help us to conquer the apostles of greed and racial arrogances. Lead us to the saving of our country, and with our sister nations into a world unity that will spell a sure peace—a peace invulnerable to the schemings of unworthy men. And a peace that will let all of men live in freedom, reaping the just rewards of their honest toil.

Thy will be done, Almighty God.

Amen.