WWII veteran and former Senate Majority Leader Bob Dole, and his wife, former North Carolina Sen. Elizabeth Dole, take part in a wreath laying ceremony at a 10th anniversary ceremony for the WWII Memorial in Washington, Saturday, May 24, 2014. (AP Photo/Molly Riley) (Molly Riley/AP)

Bob Dole (R-Kan.) is a former senate majority leader and was the 1996 Republican nominee for president.

Seventy years ago today, the map of the world, the United States’ global role and the lives of generations of Americans changed forever.

D-Day, June 6, 1944. The Allied forces’ assault on continental Europe — the largest amphibious offensive in history — doomed Nazi Germany to defeat, but for many at that moment, myself included, it seemed impossible to look so far into the future. D-Day itself was one of the deadliest days ever for Americans in battle, and hundreds of thousands more people, from dozens of nations, were yet to die: soldiers, civilians, victims of the Holocaust.

Eleven months later, the Allies celebrated victory in Europe; the Axis had run away from the countries it had overrun, and millions were liberated — although millions more from Berlin eastward were lost to tyranny behind the Iron Curtain. Many of our soldiers came home, while many others went to fight in Asia. Gravely wounded in battle approximately three weeks before VE Day, I spent the next three years in hospitals. After bouts of self-pity, I came to count myself lucky.

We owe the success of D-Day not only to rank-and-file soldiers but also to President Franklin D. Roosevelt and Gen. Dwight D. Eisenhower — visionary leaders whose achievements were rooted in their core beliefs, high standards, trustworthiness, uncanny abilities to elicit strong performances from those serving under them and embrace of the responsibilities of office.

Eisenhower, a fellow Kansan, was my hero from the moment I donned my uniform. Alone in the still hours before D-Day, he drafted a short statement to be released if his monumental operation did not succeed. “Our landings in the Cherbourg-Havre area have failed,” it read in part, “and I have withdrawn the troops . . . [who] did all that bravery and devotion to duty could do. If any blame or fault attaches to the attempt it is mine alone.”

The landings were a tremendous gamble when the stakes were at their highest. Eisenhower did his utmost to improve the odds, but two major variables were beyond his control: the weather and the Germans’ strength in preventing the landings. Both proved formidable, but our forces prevailed.

If they had not, Eisenhower would have taken full blame. This caliber of leadership is rare in war and rarer still in peacetime, yet it is needed in both. Our nation may enjoy moments of tranquility, but, internationally, there is no such thing as untroubled times. Every administration can point to foreign policy successes but sometimes must acknowledge failures and, if time permits, change course.

President Obama has implemented successful strategies in Africa, in trade with Asia, and, arguably, in the Israeli-Palestinian conflict. But he has not in Syria, the ground of which, we are constantly reminded, will not be touched by the boots of the straw-man soldiers he evokes so often. Instead of taking effective action just short of this, the administration is doing little more than trying to feed besieged civilians while waiting for Syria’s despotic leader to surrender his illegal weapons. As the slaughter continues well into a third year, our administration is still not adequately addressing the most significant moral crisis it faces.

In Ukraine, the administration has erected another straw man by hailing the non-escalation of the conflict. We are not doing enough to support what remains of Ukraine, and the administration seldom mentions Crimea, which Russia seems to have swallowed with the same permanence as it occupies its seat on the U.N. Security Council.

While conflicts and leaders come and go, one thing has not changed since D-Day: the quality of our soldiers. We who fought in World War II and the civilians who supported us are frequently called the “greatest generation.” We are now the “dwindling generation”: Of 16 million World War II veterans, about 1 million survive. More than 500 die each day. Next year, for the first time since D-Day, there will be no World War II veterans in Congress.

Those who have followed us — in wars and non-combat deployments — are as strong, brave and dedicated as we were. Thanks to modern training and weaponry, they are even more capable. Of course, these advances — and the preservation of our liberty and its pursuit abroad — come at a price, figuratively and literally, as successive presidents and Congresses have recognized in insisting on a strong national defense.

When I talk to veterans and other Americans during my frequent visits to the National World War II Memorial, I hear a refrain that may constitute the most important lesson of the war: Our nation must not become complacent. We cannot rest on the laurels that adorn this and other monuments. We must remain strong and vigilant. May God continue to bless the United States of America.